Nafs (نَفْس) is an Arabic word occurring in the Quran, literally meaning "self", and has been translated as "psyche", "ego" or "soul". In the Quran, the word is used in both the individualistic (verse 2:48) and collective sense (verse 4:1), indicating that although humanity is united in possessing the positive qualities of a nafs, they are individually responsible for exercising the agencies of the "free will" that it provides them.
In the Qur'an, when used alone, the word "nafs" is not really used as a synonym for soul (in the sense of the soul as a non-corporeal entity distinct from the body). Rather, it is usually used to refer to the complete self; for instance, in phrases like "bring yourselves" or "they deceive themselves".
(Of course, this distinction can be blurry based on how one perceives the nature of the soul and the relationship between the soul and the body.)
This is different from the use of the word "nafs" outside the Qur'an, in that "nafs" in other texts or discussions is often used to mean specifically the immaterial part of the human.
Therefore, when the Qur'an says "kullu nafsin dha'iqat al-mawt", it means that all people will taste death in a holistic sense, not specifically that all souls will.
However, since the soul and body experience things simultaneously, the soul will also taste the experience of death, just as it experiences other things occurring via the body.
If one understands death to mean "transfer from realm to realm", rather than "annihilation", then definitely the soul will experience transfer from realm to realm upon death.
Some say that we will have a different type of body as a vehicle for the soul in the barzakh and in the Hereafter. Therefore, if death is also understood to mean "transfer from one type of body to another", the soul will also taste death in that way.
So it is not incorrect to say that all souls will taste death; the usage of the word in the Qur'an is simply more expansive than that.
Note that compound phrases in the Qur'an such as nafs al-'ammarah (the bestial soul), nafs al-lawwamah (the blaming soul), and nafs al-mutma'innah (the content soul which God calls to Paradise) refer more to immaterial aspects of the human being.
Jaami' al-Sa'adaat by Shaikh al-Naraaqi.
The difference between the heart قلب and the breast or chests صدور in Quran has been discussed by many scholars of Tafseer. We see some non Shia scholars claim that there is no difference between heart and breast. We can not accept this opinion because of the clear mention of hearts and breasts in the same Quranic verses which must mean a difference in the meanings.
Among many opinions, we can say that the breast or chest is wider than the heart and it is effected by the state of mind and feeling of comfort or discomfort. That is why we read the supplication of prophet Moses (AS): O my Lord, extend my breast (Taha: 25).
The heart is our inner which is the origin of our intentions, while the breast is effected also by outside reasons and factors which make us feel comfortable or otherwise. That is why we read in Sura Al-Inshiraah how Allah (SWT) tells His Prophet Muhammad (SAWA) mentioning His bounties on him: Did not We extend your breast? ألم نشرح لك صدرك which means that Allah (SWT) Has granted him this bounty of making his breast big and extended.
In Quran we read about Quran that it is : Cure for what is in the breasts وشفاء لما في الصدور (Younus : 57). What is in breasts can be a mixture of our feelings and our thinking and reactions to other factors surrounding us.
No doubt, heart is the Centre of the breast (Hearts inside the breasts) (ولكن تعمى القلوب التي في الصدور) )(Verily, it is not the eyes that grow blind, but it is the hearts which are inside the breasts that grow blind) Al-Hajj : 46.
When we recite Durood (Salawaat) we mention the Prophet Muhammad (SAWA) and his Progeny (Ahlul Bayt)(AS) and Hazrat Ali (AS) is the head of Ahlul Bayt (AS) after the Prophet (SAWA).
Imam Ali (AS) was brought in Mubahala as Nafs of the Prophet (SAWA) while Hasan (AS) and Husain (AS) where brought as the sons of the Prophet (SAWA).
Imam Redha (AS) when Al-Ma'moon asked him about he greatest tribute of Ali in Quran, said : Mubahala when Allah mentioned Ali as Nafs of the Prophet (SAWA).
There are different ways of explaining the concept of the soul. You may want to search for the article 'Explanation of Soul or Self in the Holy Qur'an and Atman in the Ancient Upanishads' by Dr. Ali Reza Khajegir and Mohammad Reza Afroogh, in the Journal of Religion and Theology, Vol. 2, SRYAHWAR Publications.
Also, see the work by Ayatullah Ibrahim Amini on the Ma'ad in the Qur'an on this website.
If you read French, you may also want to read about the work of ‘Alaudawlah Semnānī and Qādī Sa‘īd Qummī in Henry Corbin, En Islam Iranien, pps 176-180. Here, they talk about the different levels of the soul that correpond to different levels of time. I have translated these pages if you would like me to send them.
Thank you for your question. In some translations of the Qurʾān the term nafs is translated in almost every instance it appears as the soul. This can be misunderstood as although the term is used to denote the spiritual aspect of the human in some instances, in many others it is better translated as the individual, rather than specifically the soul or spiritual aspect of the human. It is not a completely incorrect use of the word soul as it can be used to mean an individual in English too, like in the phrase: “don’t tell a soul”. It is more that we are aware of the context of such a phrase and therefore would not misinterpret it to mean “don’t tell a spiritual aspect of an individual”.
The spiritual element of a human is also referred to in other instances as the rūḥ, especially in the story of the creation of Adam (see 32:9; 15:29; 38:72), although the term rūḥ doesn’t always denote spiritual aspect of the human either (see for example 40:15; 16:2; 97:4).
The rūḥ and nafs are not interchangeable terms.
It is a later philosophical development which equates the nafs with the soul of the human and that has perhaps caused some confusion regarding the linguistic meaning of nafs used in the Qurʾān.
The term nafs and its derivatives occur more than 250 times in the Qurʾān and it denotes the individualisation of an essence. A referent of this general term is the human nafs (other referents include jinn 6:130 including Satan 18:51 and God Himself see 6:12), either:
1. in terms of its inner or spiritual aspect, with the commanding soul, al-nafs al-ammārah (see 12:18; 12:53; 20:96, 50:16; 64:16; 53:23; 59:9) where Satan whispers (see 47:25) and if fought results in heaven (see 70:40-41). The commanding self is fought with the blaming self or conscience, al-nafs al-lawwāmah (75:2) so that a person reaches a clear conscience al-nafs al-muṭmainnah (89:27)
2. or in terms of an individual, as when Moses said: “Lord, I have killed a person (nafs) among them, and I fear they will kill me!” (see 28:33; also for example 2:155; 5:45; 17:33; 18:74; 25:68; 61:11)
* Al-Muṣṭafawī, Taḥqīq fī kalimāt al-Qurʾān al-Karīm, (12) 196-199.
* Emil Homerin, “Soul” in Encyclopaedia of the Qurʾān, Brill, (5) 80-84
Nafs in the Quran is translated with terms like “yourself” and “soul”.
“And do thou (O reader!) Bring thy Lord to remembrance in thy (very) soul” in another translation “And remember your Lord within yourself” (7:205)
“And fear a Day when no soul will suffice for another soul at all” (2:48)
“There is no soul but has a protector over it” (86:4)
In the verse: “And I do not acquit myself. Indeed, the soul is a persistent enjoiner of evil, except those upon which my Lord has mercy. Indeed, my Lord is Forgiving and Merciful” (12:53) the soul is described with a specific characteristic, or at least a part of the soul is described with the ability to do evil, it might even prone to evil. The soul is described with three different qualities:
“1) The despotic soul which leads one to commit evil and vicious acts. If it is not controlled by faith and reason, it results in man’s sudden fall.
2) The reproaching soul. This self or ego is active when a guilty person blames and scolds himself. In this case, he tends to seek repentance and is apologetic for the sin or crime which he has committed.
3) The peaceful soul which is found in only the prophets, and those truly trained by them. Once they find themselves surrounded by unbridled passion and ignorance, they seek the help of Allah to be extricated from it. They owe everything to Allah who loves them very much.” (From: An enlightening commentary into the light of the Holy Qur’an: https://www.al-islam.org/enlightening-commentary-light-holy-quran-vol-7/...)
In the verse: “By the Soul, and the proportion and order given to it; And its enlightenment as to its wrong and its right; He has succeeded who purifies it” (91:7-9), we are taught that God taught man how to discriminate between right and wrong (https://www.al-islam.org/enlightening-commentary-light-holy-quran-vol-20...). Further explained in the commentary of the Holy Qur’an:
“The purpose of using the term /taqwa/ based on /wiqayah/ with the meaning of 'protection', is that Man protects himself from sin, crime, corruption and vice.
It is necessary to note that verse 8 does not mean, as some have considered, that Allah put the means of committing / fujur/ and /taqwa / inside the soul of Man; the very means which cause him to do wrong actions and break the curtains of piety, or the means and ways that push him towards piety and good actions.
They have thought of the verse as an evidence for the existence of some contrariety in the entity of Man.
It says that Allah inspired him and taught him these two facts.” (https://www.al-islam.org/enlightening-commentary-light-holy-quran-vol-20...).
The soul is inspired by God, as it is explained in the commentary:
“the soul is inspired by Allah; its Almighty and All-wise Author, with the consciousness and the faculty of discretion to distinguish between piety and impiety, right conduct and the wrong ways in life, by the means of his 'wisdom' and 'primordial nature'.
This is why some commentators believe that this verse, in fact, refers to the proposition of the idea of 'rational goodness and rational badness' and that Allah has gifted Man with the ability to distinguish between them.
It is noteworthy that Allah has given Man many blessings, but, among all of them the Qur'an emphasizes, here on the inspiration of understanding 'piety' and 'impiety' and the recognition of right and wrong, because this is the most important factor in the destiny of Man.
Finally, after these numerous important oaths, attention is paid to the result of them and says:
"Indeed he succeeds who purifies it,"
The term /zakkaha/ is based on /tazkiyah/ which originally means 'to grow’; and /zakat / basically means 'growth'.” (https://www.al-islam.org/enlightening-commentary-light-holy-quran-vol-20...).
The purpose of the creation of man (the soul) is for the creations to find nearness to God. Obtaining nearness to God is the only true happiness (bliss) one may experience. The only happiness that lasts. The soul is in constant longing for happiness, and searches for it. The soul has to be purified in order to see and understand the true goal of creation, otherwise it will search for temporary happiness in worldly or harmful affairs. God has already inspired the soul to do good, and to reach it’s purpose the soul was gifted with tools and merits for this aim. “Such as; a wakeful conscience and a sense of understanding piety and impiety for paving the way to felicity.” (https://www.al-islam.org/enlightening-commentary-light-holy-quran-vol-20...).
For further readings, go to the “Shi’ite Creed” by Shaykh Saduq pg. 32 (https://www.al-islam.org/printpdf/book/export/html/12317)