The words (God has forgiven thee) refer to the following utterance of God Almighty in Surat al-Fath:
Surely We have given thee a manifest victory (fath, which also means 'opening'), that God may forgive thee thy former and thy latter sins .... (48:1--2)
The `ulama' - may God be pleased with them - have suggested various explanations for this noble verse so as to reconcile it with the Noble Prophet's infallibility (`ismah). Here we will cite some of those explanations mentioned by the marhum `Allamah Majlisi, may God Almighty's mercy be upon him. Thereafter we will briefly mention that which the `urafa' have said in this regard in accordance with the teachings of the mystic path.
Marhum Majlisi says: The Shi'ah have offered various views regarding the explanation (tawil) of this verse. According to one of these, the `sins' (dhunub; singular dhanb) mentioned there mean the sins of the Ummah which are forgiven by the Prophet's intercession. These sins of the Ummah have been attributed to him because of the connection that exists between him and it. This possibility is supported by the following narration of Mufaddal ibn `Umar from al-'Imam al Sadiq (A):
Mufaddal says: "A man asked the Imam concerning this verse. He replied: 'By Allah, he (i.e. the Prophet) had no sin of his own. However, Allah, subhanahu, has insured that He would forgive the sins, whatever they have committed, of those who followed 'Ali (shi'at 'Ali)."
'Umar ibn Yazid narrates that al-'Imam al-Sadiq (A) said: "He had not committed any sin, not even intended to commit any. However, God made him bear the burden of the sins of his followers and then forgave them on his account. 
This author says: This explanation has a significant basis in the teaching of the `urafa' and it would not be without benefit to mention it briefly. You should know that it has been proved, in the place proper to such a proof, that the unchanging essence ('ayn-e thabit) of the Perfect Man (insan-e kamil) is the manifestation (mazhar; pl. mazahir) of the Greatest of Divine Names (ism Allah al- a'zam), which is the prototype (imam) of all prototypal names. The essences (a'yan) of all other existents subsist in the shadow of the essence of the Perfect Man on the level of knowledge and the world of essences, and exist therein on the level of being and the world of realization (`alam-e tahaqquq).
Hence the essences contained in the entire realm of existence are the manifestation of the essence of the Perfect Man, and all the existents are manifestations of his beauty and glory in the world of manifestation. Accordingly, every shortcoming that occurs in the world of exteriorization and every sin that appears in the mazahir (manifestations), whether on the level of creation (takwin) or on the level of volitional action (tashri'), is attributable to the zahir (i.e. that which is manifested through the rnazahir) in accordance with the necessary relation between zahir and mazhar. This attribution is not metaphorical, but literal and factual. It is the reality of this relation which is pointed out in the following verses:
...Whatever evil visits thee it of thy self. (4:79)
Say: 'Everything it from God. (4:78)
And reference to this matter occurs a lot in the Noble Prophet's traditions:
We are the foremost and the last ones. 
Adam and whoever that came after him shall stand under my standard on the Day of Resurrection. 
The first thing that God created was my light. 
(Before Adam was created) we glorified (God) and following us the angels glorified (Him We extolled (His) sanctity and following us the angels called Him Holy . 
Had we not existed, God would not have been known. 
(God said to the Prophet:) Had you not been, I would not have created the heavens. 
We are the face of God. 
It is stated in a tradition that "the Messenger of Allah - may Allah's peace and benedictions be upon him and his progeny - (in relation to the community of the faithful) has the position of the tree's trunk; the Imams of Guidance, may peace be upon them, are its branches; their followers (shi'ah) are like the leaves of the tree."'  Hence the beauty of the sacred tree of wilayah is manifested through the mazahir. Should one of the mazahir suffer a shortcoming, that will affect the sacred tree.
Hence the sins of all the existents are the sins of the Absolute Master (al-wali al-mutlaq), and God Almighty, with His encompassing mercy and all-inclusive forgiveness, has showered His grace upon the Noble Prophet - may God's peace and benedictions be upon him and his progeny -, declaring, `The sins of the former people and the sins of those to come will be covered by My encompassing mercy and the entire realm of being shall attain its ultimate felicity through your shafa'ah (intercession), and:
The last to intercede is the most merciful of the merciful ones. (i.e. God).
According to this teaching the noble verse at hand fulfils the promise given in another verse, which says:
And thy Lord shall soon give thee, and thou shalt be satisfied. (93:5)
And it has been said of this verse that it is:
The most hope-giving of verses in the Qur'an. 
Hence according to this teaching `the former sins' may possibly mean the sins of the earlier ummahs (umam) for all the ummahs are part of the Ummah of this sacred essence (the Prophet) and all the calls (da'wahs) of the prophets represent invitation to the ultimate shari'ah, being the mazahir of al-Wali al-Mutlaq, and `Adam and whoever that came after him' are the leaves of the tree of wilayah.
The second explanation is the one given by al-Sayyid al-Murtada, may God be pleased with him. He says that dhanb is a masdar (verbal noun) and it may permissibly be referred or adjoined to the fall or maful. Here it has been related (in the construct phrase dhanbika) to the maf'ul. Hence the verse (48:2) means, "The former sins of theirs against thee in preventing thee from entering Makkah and al-Masjid al-Haram." The meaning of maghfirah or ghufran (which also means `covering) here, according to this explanation, is the abolishment and removal of the persecution that he (the Prophet [S]) faced at the hands of his enemies. The verse then means: "On the occasion of the victory and through it God would end and cover the humiliation inflicted upon you, and with the conquest of Makkah you would soon enter the city triumphantly." Accordingly ghufran has been made the recompense for jihad and the benefit of victory.
The Sayyid, upon whom be God's mercy, says: If maghfirah here is taken to mean the forgiving of sins, a reasonable meaning cannot be derived from the verse, for forgiveness of sins has no relation whatsoever with victory, nor can it be considered to be the object and benefit of victory. As to the phrase there is nothing objectionable in taking it to mean "whatever of the atrocities that have been afflicted on you and your people in the past."
Thirdly, the verse is explained to mean, "If you have committed a sin in the past or in case you commit any hereafter, I shall indeed forgive you." This is a conditional proposition (of the type `If A then B ) and it is not necessary that its two sides should be factually true.
Fourthly, by `sin' here is meant omission of mustahabbat (supererogatory duties), for the Prophet (S) never defaulted in performing the wajibat (obligatory duties). And it is possible that due to his elevated and exalted station, that which is not considered to be sin for others may be considered sin in relation to him.
The fifth explanation is that this verse is intended to glorify the Prophet (S) and is equivalent to a eulogy, as when one says:
Sixthly, al-Majlisi says:
Al Saduq in 'Uyun akhbar al-Rida has reported with his isnad from 'Ali ibn Muhammad ibn al-Jahm that he said: "I was present in al-Ma'mun's gathering when al-Rida, upon whom be peace, was also with him. There al-Ma'mun said to him: 'O son of the Messenger of Allah, don't you claim that the prophets are secure from error (ma'sumun)?' He replied 'Yes'. Al-Ma'mun said: 'Then what is the meaning of the utterance of God, "Al-Rida, upon whom be peace, replied, 'The polytheists of Makkah did not consider anyone a greater sinner than the Messenger of Allah, upon whom and whose progeny be God's peace and benedictions, because they worshipped instead of Allah three hundred and sixty idols. When the Prophet - may God's peace and benedictions be upon him and his progeny - came to them with the call to pure monotheism (ikhlas), it appeared to them as a monstrosity, and they declared: "What, has he made the gods One God? This is indeed an odd thing .... Go! Be steadfast to your gods; this is a thing to be desired. We have not heard of this in the last religion, this is surely an invention." (38:5-7 ).
"'When God Almighty opened Makkah to His Prophet - may God's peace and benedictions be upon him and his progeny - He said to him: "O Muhammad! Surely We have opened for thee a manifest opening, that God may forgive thee what the polytheists of Makkah regarded as thy former and latter 'sins' on account of thy call to the Unity of God." Some of the polytheists of Makkah had embraced Islam and some had left Makkah, and those who remained there had no, power to repudiate the Prophet's call to tawhid. In this way that which was the Prophet's sin in their eyes came to be condoned by means of his domination over them.' Thereat al-Ma'mun said: 'You are wounderful, O Abu al-Hasan!' " 
This writer says: This was the sixth explanation of the blessed verse that occurs in the noble hadith. According to it the meaning of `sin' here is that which appeared to the polytheists as sin in conformity with their corrupt claims.
A Mystical Interpretation:
You should know that there is an interpretation of the noble verse based on the teachings of the gnostics and the people of the path of the heart. In order to describe it, it is necessary to mention what they call the `Threefold Openings' (or the `threefold victories', futuhat-e thalathah). Fath in their teaching means the opening of the doors of gnosis and gnostic experience or. the wayfarer by God after that these doors have remained closed and locked upon him. So long as man remains in the dark abode of the self and tied to its attachments, all the doors of gnosis and gnostic experience remain locked upon him. But as soon as he comes out of this gloomy habitat by means of the force of austerities and the lights of guidance, and leaves behind the stages of the self, the door of the heart is opened upon him and gnostic truths manifest themselves in his heart, and he attains to the `station of the heart' (maqam-e qalb). This stage is called fath-e qarib (the nearer opening), for the first of the openings is the nearest of them. It is this fath that is referred to in this utterance of God Almighty:
...help from God and a nigh opening. (61:13)
Of course, it is with God's help and assistance and with the guiding light and magnetism of that Sacred Essence that this and other openings take place.
However, as long as the wayfarer remains in the realm of the heart ('alam-e qalb) and is subject to the rituals and duties of the heart, the door of the Attributes and Names remains closed and locked upon him. When, thereafter, the irradiations of the Names and Attributes lead to the dissolution of the `alam-e qalb and when those irradiations bring the heart's attributes and excellences to extinction, that which occurs is the fath-e mubin (the manifest opening). Thereat the door of the Names and Attributes is opened upon the wayfarer, the earlier rituals of the self (nafs) and the latter ones of the heart (qalb) becoming effaced and covered (maghfur) by the covering grace (ghaffariyyat wasattariyyat) of the Names. Hence they say that to this refers the utterance of God, the Exalted:
That is, We have opened for thee the manifest opening to the realm of the Names and Attributes, so that thy sins, relating to the earlier station of the self and the latter station of the heart, are covered by the covering grace of the Divine Names. And this is the opening of the door of wilayah. As long as the wayfarer is behind the curtain of the pluralities of the Names (katharat-e asmai) and the particularities of the Attributes (ta'ayyunat-e sifati), the doors to the irradiations of the Essence are locked upon him. But when he receives the irradiations of the Essence of the One, all the rituals relating to the realms of khalq and amr become extinct, submerging the devotee in essential synthesis, and the fath-e mutlaq (the absolute opening) is attained. Thereupon, the absolute sin (dhanb-e mutlaq) is enveloped (maghfur) and the essential sin (dhanb-e dhati), which is the source of all sins, is covered by the irradiations of the One.
Your existence is a sin to which no (other) sin is comparable.
And, they say, it is to this fath that the following utterance of God, the Exalted, alludes:
When comes the help of God and the opening. (110:1)
Hence it is with fath-e qarib that the doors to the heart's gnosis are opened and the sins relating to the (carnal) self (dhunub-e nafsiyyah) become forgiven. With fath-e mubin the doors of wilayah and Divine irradiations are opened and the remaining traces of the earlier sins of the self and the latter sins of the heart are forgiven. And with fath-e mutlaq the door is opened to the irradiations of the Divine Essence and the absolute essential sin is forgiven.
It should be known that fath-e qarib and fath-e mubin are something which the awliya ; prophets, and `urafa' share with others; but fath-e mutlaq is a station that is exclusively and ultimately theirs, and should anyone succeed in attaining it, it is only through the mediation of those elevated spirits.
This discourse reveals that there are various levels of sin and sinfulness. Some of them are considered virtues for the virtuous but are sins for the immaculate. It is reported that the Noble Messenger, may God's peace and benedictions be upon him and his progeny, stated:
In order that my heart should not gather rust, I seek the forgiveness of God seventy times a day. 
This rusting may be attention to plurality, although it may be on the level of passing, stray thoughts. And it is mentioned in the hadith that the Messenger of God, may God's peace and benedictions be upon him and his progeny, would not leave any gathering without seeking God's forgiveness twenty-five times. 
These traditions show that istighfar is not solely limited to such sins as are contrary to ismah (inerrancy), and 'dhanb' and 'maghfirah' here (in the context of the prophets and awliya') do not have their ordinarily understood signification. Therefore, this noble verse is not contradictory to the Prophet's elevated spiritual station; rather, it affirms and confirms it. This is because seeking forgiveness for the sins related necessarily to the various stages of spiritual development are a necessary aspect of spiritual wayfaring and ascent to the heights of human perfection, since every being that exists in this world is the offspring of this corporeal and physical realm and possesses all its accompanying mulki, animal and human functions, some of these potentially and some of these in actuality.
Hence should anyone want to make the journey from this realm to the other realm and from there to the realm of Divine proximity, he should pass through all the intermediary phases and stages. And whenever he attains to a higher stage, he is forgiven the sins of the preceding stage, until he attains to the ultimate station where all his sins are forgiven under the irradiations of the Essence of the One. Thereat, the existential sin (dhanb-e wujudi), which is the source and fountainhead of all sins and sinfulness, is covered and effaced under the shadow of the Majesty of the One. This is the highest point in the ascent of a being towards perfection. It is here that the station of `death' and complete annihilation is achieved. And therefore when the noble verse: was revealed, the Noble Messenger, upon whom be God's peace and benedictions, said: "This surah is the news of my death." And God knows best. 
The Reality of Shukr:
You should know that thankfulness means appreciation of the ni'mah (favour, blessing, bounty) provided by the Provider (Mun'im) and the appearance of the effects of this appreciation in the heart, on the tongue, and in bodily acts and movements. As to the heart, the effects there are of such nature as humility, awe, love and the like. As to the tongue, the effects there appear as praise and glorification. As to the bodily members, the effects consist of obedience, the use of the bodily members for the good pleasure of the Mun'im, and the like. According to al-Raghib:
Thankfulness (shukr) is the contemplation of the ni'mah and its expression. 
It has been said that shukr is the (partial) inverse of kashr, meaning kashf (uncovering, discovery), and its antonym is kufr, which means forgetfulness and concealing of ni'mah. Dabbah shakir' (grateful animal) is one which expresses the appreciation of its master and provider by its fatness and robustness. It has also been said that its origin is 'aynun shakra, shakra here meaning mumtali'ah (full). Accordingly, shukr means being full of the mention of the Mun'im (Provider). Shukr is of three kinds: the shukr of the heart, which is the contemplation of ni'mah; the shukr of the tongue, which is praise of the Mun'im; and the shukr of all other bodily members, which is heedful observance of the ni'mah as it deserves to be observed (i.e. recognized, and used for the purpose proper to it).
The confirmed gnostic Khwajah 'Abd Allah Ansari says: "Shukr is a name for the knowledge (marifah) or ni'mah, for it is the means of knowing the Mun'im". The learned interpreter of his work says:
The contemplation of ni'mah as belonging to the Mun'im and the knowledge that it is from Him is shukr itself. It has been narrated that Hadrat Dawud (David), upon whom be peace, said: "O Lord! How can I thank Thee, for my thankfulness is another bounty (ni'mah) of Thee that itself requires thanksgiving!" God revealed to him: "O Dawud, when you have known that every ni'mah that you enjoy is from Me, you have thanked Me."
This author says: That which these scholars have said is based on some lack of precision, for shukr is not the heart's knowledge per se or expression of it by the means of the tongue or bodily acts. Rather, it is a psychical state (halat-e nafsaniyyah) which itself results from the knowledge of the Mun'im. The acts of the heart and the body are the fruits of this state. What some scholars have said is close to this, although their statements too are not totally free of loose thinking. They have said:
It should be known that shukr is compensating for ni'mah through word, deed and intention. It rests on three supports.
Firstly, the knowledge (ma'rifah) of the Mun'im and the attributes befitting Him, as well as the knowledge of ni'mah as ni'mah per se. This knowledge does not become perfect unless one understands that all the apparent and hidden bounties are from God Almighty and that it is His Sacred Essence that is the real provider. All the means and intermediaries, whatever they are, are subject to His law and command.
Secondly, it is a state which is the result of this knowledge, which consists of humility, awe, and delight for the bounty as a gift that indicates the Mun'im's care and attention for you. Its sign is that you should not be delighted by the world except for something that causes nearness to God.
Thirdly, it is action that results from this state; for when this state appears in the heart it produces an impulse for action aimed to achieve nearness to God. That action is related to the heart, tongue and other members. As to the heart, its action consists of the veneration, praise and glorification of the Provider, the contemplation of His creation, His acts, the effects of His grace. and His beneficence towards all His creatures. As to the tongue, its action consists of the expression of that beneficence through praising, glorifying and extolling God and declaring Divine unity, as well as through, discharging the duty of al-'amr bi al-ma'ruf wa al-nahy an al-munkar and other duties. As to the bodily members, their thanksgiving action lies in using the outward and inward bounties in obedience, worship and in preventing sin against God and violation of His commands. Thus the eye should be used for studying His creation, reading His scripture, and teaching the traditional sciences of the prophets and the awsiya', may peace be upon them. Similarly for the other bodily members. 
Ignorance and Ingratitude:
You should know that shukr for the inward and outward bounties of God Almighty is one of the obligatory duties of servanthood and creaturehood, which everyone must attempt to fulfil to the extent of his capacity, although no creature can adequately fulfil its obligation of thanking God Almighty. The ultimate limit of thankfulness is the knowledge of the incapacity to satisfy it fully, in the same way as the ultimate limit of servanthood is the realization of the incapacity of fulfilling its demands - and hence the Noble Messenger, may God's peace and benedictions be upon him and his progeny, confessed to his incapacity, although none of the existents has attempted to discharge the duties of servanthood and gratitude to the extent of that holy master -because the perfection or inadequacy of gratitude is subject to the gnosis of the Munim and the knowledge of His bounties. (Since this gnosis and knowledge are never complete), no one can satisfy the rights of gratitude.
The servant becomes fully thankful (shakur) when he knows the relation of creation to the Creator, and has gnosis of the entire spread of Divine beneficence, from its beginning to end, of the interrelations of the bounties with each other as well as of the beginning and end of the stream of existence in its true reality. And this gnosis is not attainable for anyone except the elect of the awliya', the noblest and best of whom is the sacred essence of the Seal of Prophethood, may God's peace and benedictions be upon him and his progeny. All others are devoid of some or rather most of those stations. Rather, as long as the reality of Divine efficacy does not make an imprint on the devotee's heart and as long as he does not attain conviction that
There is no efficient agency in the realm of existence except Allah,
the darkness and obfuscations of shirk and doubt (shakk) remain in his heart and he cannot thank God as he should. One whose gaze is fixed on causes and means and one who considers the efficacy of existents to be independent, does not relate the bounties to the Lord of bounty, and here lie the roots of ingratitude to God Almighty. Such a one has carved out idols, each of which he considers to be efficient. At times he relates actions to his own efficacy and even considers himself as having control over events and affairs. At times he considers the natural aspects of the world of existence as being efficient, and at times he relates the bounties to their apparent dispensers while considering God to be bereft of any efficacy, believing God's hands to be fettered, whereas:
Fettered are their hands, and they are cursed for what they have said (5:64).
God's dispensing hands are free and the entire realm of being in reality belongs to Him and no other has any role in it. Rather, the entire universe is the manifestation of His power and bounteousness and His beneficence envelopes everything. All bounties are from Him and no one has any bounty of his own that he may be its provider. Rather, the realm of existence owes its being to Him, and others have no (independent) being so that anything may be attributed to be them. However, the eyes are blind, the ears are deaf and the hearts have curtains drawn upon them.
I want a vision that may pierce the (curtain of) causes.
How long shall these dead hearts of ours remain ungrateful toward God's bounties, and relate them to the world, its circumstances and persons? These attachments and attentions amount to ingratitude towards the bounteousness of the Sacred Essence and to Its concealing grace. This shows that fulfillment of the demands of gratitude is not everyone's job, and that Sacred Divine Essence. the Glorious and the Exalted, has declared: That is, there are few servants who have adequate gnosis of God's bounties or know them as they deserve to be known. And, therefore, there are few servants who stand up to fulfil the duties of gratitude.
The Different Levels of Shukr:
And it should be known that even as the levels of knowledge of the servants of God are different, so also are their levels of thankfulness. The levels of gratitude are also different because shukr is the praise of the Provider for His bounties. Thus the outward kinds of bounties require one kind of gratitude and the inward bounties a gratitude of another kind. If the bounty is of the category of knowledge and gnosis, its shukr is of one kind, and if it is of the category of the irradiation of Divine Names it is of another kind, and if of the category of the irradiation of the Divine Essence, it is of yet another kind. And since all the categories and levels of bounties are enjoyed only by a few of His servants, the effort to fulfil the duties of gratitude at all levels is only possible for a few. Those being the sincere (khullas) awliya', who, in their being, encompass the entire range and levels of being (jami' jami'-e hadarat), being the limit of all limits (barzakh-e barazikh), and encompasses all the exoteric and esoteric levels. Accordingly, their thanksgiving (shukr) is accomplished through all the apparent, inward, and the inmost tongues.
Although shukr has been said to be one of the stations pertaining to the common people because of its proximity to the claim to the requital of the Provider - and this is considered to be irreverence - however, such a proximity exists only for ethers than the awliya', especially the perfect (kummal) among them, who encompass the full range of being and possess the station of unity and plurality. Therefore, the adept gnostic Khwajah `Abd Allah Ansari, who, although he states that shukr is one of the stations of the common people, adds:
That is, the third degree of shukr lies there where the servant does not see anything except the beauty of the Mun'im, being immersed in His beauty. That consists of three stations. First, he observes Him as the humble slave contemplates his master. In this state, unaware of himself in His presence, he is fully immersed in reverence, not setting any worth upon himself. When in this state of humility, if he is bestowed any bounty, he values it greatly, considering himself as insignificant and unworthy of it. Second, his observation is that of a lover observing his beloved. In this state he is immersed in the beauty of the Beloved and whatever he receives from Him, cherishing it, though it be affliction and hardship. Third, he observes Him without the limitations of the Names, or rather has the epiphany of the Essence itself. In this state he forgets himself and others and sees nothing but the Divine Essence, and is conscious neither of any bounty nor adversity.
This shows that the first stage in all the stations of the wayfarers is the one tread by the common people, and the ultimate stages in all the stations pertain exclusively to the sincere (khullas) or rather to the perfect (kummal) (of the awliya').
The Station of Shukr in Hadith:
We shall complete this section with the mention of some traditions relating to shukr.
In al-Kafi, al-Kulayni narrates with his isnad from Abu 'Abd Allah (A) that he said: "'The Messenger of Allah, may Allah's peace and benedictions be upon him and his progeny, said: 'One who takes food with gratitude has a reward like the one who fasts exercising vigilance over himself. The healthy person grateful for his health has a reward like the one who bears his (bodily) afflictions patiently. And one who gives gratefully has a reward similar to the one who bears his deprivation with continence.' 
Al-Kulayni reports with his isnad from 'Ubayd Allah ibn al-Walid that he said: "I heard Abu 'Abd Allah (A) say: 'There are three things in whose presence nothing can harm one: prayer in affliction, seeking God's forgiveness for one's sins, and thanksgiving for God's favours.' " [l9]
Al-Kulayni reports with his isnad from Abu Basir that Abu 'Abd Allah (A) said: "Verily one of you drinks water and God assigns paradise to him on that account." Then he (A) added: "Verily, one who takes the vessel (containing water), brings it to his mouth, then takes God's Name, then drinks from it, then draws it away while desiring it, then praises God, then drinks from it again, then takes it away while he desires it, praises God, then drinks from it again, then sets it aside and praises God, God, Almighty and Glorious, makes the paradise obligatory for him." 
Praise of God is the purveyer of gratitude, and, as has been stated in many traditions, one who says "Al-hamdu lillah' (All praise is God's) has offered his thanks to God. Al-Kulayni, in the noble al-Kafi, narrates this tradition through his isnad from `Umar ibn Yazid:
'Umar ibn Yazid says: "I heard Abu 'Abd Allih (A) say: The (adequate mode of) thanksgiving for all favours, however great they may be, is that you praise God, the Almighty and the Glorious, on their account.' " 
Al-Kulayni reports with his isnad from Abu 'Abd Allih (A) that he said: "Gratitude for God's gifts lies in abstaining from what He has made unlawful. One's thanksgiving is complete when one says: 'Praise be to Allah, the Lord of the worlds.' " 
Al-Kulayni reports with his isnad from Hammad ibn 'Uthman that he said: "Al-'Imam al-Sadiq (A)once came out of the mosque to find his mount missing. Thereupon the Imam (A) said: 'Should God return it to me, I will thank Him as He deserves to be thanked.' It was not long before the animal was brought to him. Thereat, the Imam (A) said: 'Al-hamdu lillah.' Someone said to him: 'May I be made your ransom, didn't you say that you will thank God as He deserves to be thanked? Al-'Imam al-Sadiq (A) said to him: 'Didn't you hear me say 'Al-hamdu lillah?' " 
This tradition shows that the praise of God is the best of the ways of oral thanksgiving. Among the effects of thanksgiving is increase in ni'mah, as mentioned unambiguously in the Noble Scripture:
if you are thankful, surely I will increase you .... (19:7)
And the noble al-Kafi has recorded this mustanad tradition of al-'Imam al-Sadiq (A) in this regard:
Al-'Imam al-Sadiq (A) said: "One who has been given thankfulness has been also given increase (in ni'mah) Allah, Almighty and Glorious, says: 'If you are thankful, surely I will increase you." 
You should know that `A'ishah had imagined that the motive behind worship was confined to the fear of punishment or the effacement of sins. She had imagined that the worship of the Noble Prophet, upon whom and whose progeny be God's peace and benedictions, was like the worship of other people. Therefore she had wondered as to why the Prophet (S) took so much pains. This thought was as much due to her ignorance of the station of worship and servanthood as due to the ignorance of the station of prophethood and messengerhood. She did not know that the worship of slaves and hirelings was foreign to the sacred station of that master. The majesty of the Lord and gratitude for His unlimited bounties had made comfort and ease foreign to his holy being. Rather, the worship of the sincere awliya' is the stage of the boundless irradiations of the Beloved, as pointed out in the prayer of the heavenly ascent. The holy awliya', upon whom be peace, while being absorbed in the beauty and glory of the Beloved and effaced in His attributes and Essence, are never negligent of any of the stages of servanthood. Their bodily movements are subject to their spiritual stirrings, suffused with love, which are subject to the quality of the manifestation of the Beloved's beauty. However, to satisfy someone like `A'ishah it is not possible to give any but a perfunctory explanation. Hence, the Prophet (S) confined himself to mentioning one of the lower stations so as to make her understand that the worship of that master was not aimed at such base purposes. And all praise is God's.
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'Ali ibn Ibrahim, in his tafsir, reports with his isnad from Abu Ja'far (A) and Abu 'Abd Allah (A) that they said: "The Messenger of Allah (S) used to pray while standing on his toes, until his feet became swollen. Thereupon Allah, Blessed and Exalted, sent down the verse: 'Taha...' (20:1-2) It meant: "O Muhammad! We have not sent down the Qur'an upon thee to put thee to hardship." 
Al-Saduq in Ma'ani al-'akhbar reports with his isnad from Sufyan al-Thawri from al-'Imam al-Sadiq (A) that he said in the course of a long tradition: "As to Taha, it is one of the names of the Prophet, upon whom and whose progeny be God's peace and benedictions, and it means: 'O seeker of the Truth (talib al-Haqq) and the Guide towards it (al-hadi ilayh).' "
And it has been narrated from Ibn `Abbas and others that Taha means `O Man'. It has been narrated from some Sunni scholars (`ammah) that Ta refers to the purity (taharah) of the Holy Prophet's heart and Ha refers to its receiving guidance (hidayah) towards God. And it has been said that Ta means the delight (tarab) felt by the inhabitants of paradise and Ha signifies the disgrace and degradation (hawan) felt by the inmates of hell. Al-Tabrisi, upon whom be God's mercy, says: "It has been narrated from al-Hasan that he would read (Ta ha) as Tah () with fathah on the ta and sukun on the ha. Should this reading of his be correct, then it must originally have been ta, with the hamzah having changed to ha. Then the meaning of the verse becomes:
Take the earth under both of thy feet. " 
There is a severe disagreement about the significance of the isolated letters (al-huruf al-muqatta`ah) at the beginning of the Qur'anic surahs. That which seems more likely is that they are of the kind of secrets exchanged between lovers, of whose significance others do not partake. The conjectures advanced by some exegetes in this regard are mostly without any source. The tradition narrated by Sufyan al-Thawri also indicates their being secret symbols, and it is not very improbable that they relate to matters which lie beyond human comprehension. Through them God Almighty has addressed His elect, and there is nothing that is mutashabih (in the Qur'an) but that they know its interpretation.  Shaqa' and shaqawah (whose derivative tashqa occurs in 20:1) are antonyms of sa`adah (felicity) and mean hardship and trouble. This is what al-Jawhari states:
Al-Tabrisi narrates this tradition in his al-'Ihtijaj:
Al-'Imam Muse ibn Ja'far (A) narrates from his ancestors (A) that Amir al Mu'minin (A) said: "For ten years the Messenger of Allah, may Allah's peace and benedictions be upon him and his progeny, stood on his toes (in his prayers) until his feet became swollen and his face turned yellowish. He would stand all the night until he was reproached in this regard. God Almighty said to him: 'Taha, We have not sent down the Qur'an upon you to cause you hardship'. That is, We have sent it down upon you that you may be felicitous and happy thereby.' "
And it has been narrated from al-'Imam al-Sadiq (A) that the Prophet (S) would lift one of his blessed feet during worship in order to make it harder upon himself. 'Thereat God Almighty sent down this noble verse. Some exegetes have opined that this noble verse is intended as an answer to the polytheists who said that the Prophet had fallen into hardship by abandoning their faith.
The perfect `arif Shahabadi, may his shadow endure, used to say:
After some time that that blessed being (i.e. the Prophet) invited the people to his creed and it did not prove to be as effective as he wished, that master thought that perhaps there was something lacking in his call. Thereafter he devoted himself to austerities for a period of ten years, until his blessed feet became swollen. Then the noble verse came down: Don't subject yourself to hardship. You are pure, and a true guide. The defect is not in you but in the people, and that:
Thou guidest not whom thou likest, (but God guides whom He wills) .... (28:56)
In any case that which we infer from the noble verse is that the Prophet (S) used to devote himself to austerities and hardships, and this is what we understand on the whole from the sayings of the exegetes, although they differ regarding the exact character of those austerities. This should be an example and a lesson for the Ummah, especially for the learned who wish to call people to God. That blessed being, with his purity of heart and perfectness would subject himself to such austerities and pains until he was asked to relax by the noble verse sent down by the Sacred Divine Essence. And we, with all the enormous burden of our sins and offences, are never mindful of our hereafter, resurrection and return, as if we have been guaranteed immunity from punishment and security from hellfire! The reason of it is nothing but that the love of world has stuffed its cotton into our ears and we no longer listen to the words of the Prophets and the awliya'.
. Al-Kafi, ii, "kitab al-'iman wa al-kufr" "bab al-shukr," hadith no.2.
. Bihar al- anwar, xvii, 76.
. Ibid., xxiv, 1-9.
. Ibid., xvi, 402.
. Ibid, xv, 3 ff.
. Al-Saduq, 'Uyun akhbar al-Rida, i, 263.
. Bihar al- anwar, xxvi, 247.
. 'Ilm al-yaqin, i, 381.
. Al-Saduq, Kitab al-tawhid, 150.
. Al-Mufid, al- Amali, majlis no. 28, p. 245.
. Al-Tabrisi, Majma' al-bayan, x, 505.
. Bihar al-'anwar, xvii, 73-76, cf. 'Uyun akhbar al-Rida, i, 202, bab 15.
. Sahih Muslim, "kitabal-dhikr'," 41; al-Shaykh al-Bahai, al-'Arba'in, in the exposition of hadith no. 22, with the words, "hundred times" (mi'at marrah)
. Safinat al-Bihar, ii, 322.
. Tafsir Nur al-thaqalayn, v, 689.
. Al-Raghib al-Isfahani, al-Mufradat fi gharib al-Qur'an, p. 265.
. This is a summary of al-Ghazili's discourse from al-Fayd al-Kashani's al-Mahajjat al-bayda', vii, 144-149.
. Al-Kafi, ii, "kitab al-'iman wa al-kufr," "bab al-shukr," hadith no. l.
. Ibid., hadith no.7.
. Ibid., hadith no. 16.
. Ibid., hadith no. 11.
. Ibid., hadith no. 10.
. Ibid., hadith no. 18.
. Ibid., hadith no. 8.
. Tafsir al-Qummi, ii, 58.
. Ma'ani al-'akhbar, 22.
. Al-Tabrisi, Majma' al-bayan; earlier to this command the Prophet (S) used to pray while standing on one foot.
. This refers to verse 28:56.