21. "Surely Hell lies in ambush"
22. "For the transgressors a destination".
23. "To abide therein for ages".
24. "Nothing cool shall they taste therein, nor any drink".
25. "Except a boiling fluid and pus".
26. "A fitting recompense (for their evil)".
27. "Surely they used not to look forward to the reckoning (for their
28. "And they rejected Our Signs with strong denial".
29. "And everything have We recorded in a book".
30. "So taste you (the fruit of your deeds); for no increase shall We grant
you, but in punishment".
Hell is a Great Ambush!
After presenting some of the evidences of Resurrection and a part of its incidents, attention is paid to the destiny of the Unbelievers and says:
"Surely Hell lies in ambush",
"For the transgressors a destination".
"To abide therein for ages".
The term/mirsad/ is a place-noun which means 'a place of observation, or of ambush'. Raqib cites in his book Mufradat: '/marsad/ and /mirsad/ both mean the same thing with a slight difference; that /mirsad/ is called a place that is made especially for an ambush'.
Some commentators have said that the term is in the Arabic intensive form, with the same sense as that of a person who lies in ambush, continuously. Of course, the first meaning is both more common and more appropriate.
The question of 'Who is lying in wait, in Hell, for the transgressors?', has been answered with 'the angels of chastisement', because according to Sura Maryam, No. 19, verse 71 the whole of mankind, good or evil, will pass by the fire of Hell or over it, thus: "Not one of you but will pass over it: this is with thy Lord, a Decree which must be accomplished". In this companion passage, the angels of chastisement are lying in wait to catch the transgressors.
If we comment on the term with the meaning of its Arabic intensive form, Hell is lying in wait and each of the transgressors, who passes by, will be absorbed inside, and in this passage it can be seen that none of them will he safe from fire since, either the angels of chastisement or the intensive absorption of Hell, will capture them.
The term /ma' ab/ means: 'a place of return', and sometimes means: 'residence'. It is used, here, with the latter meaning.
The term /ahqab/ is the plural form of /huqb/ with the sense of 'a long space of time'. The 'space' has been commented on, differently, as to being 'forty', 'seventy' or 'eighty' years. In any case, this sense denotes that the transgressors will remain in Hell for a long time, but it will end at last. This contrasts with the verses that denote the eternity of chastisement for them.
The commentators have followed different tracks in commenting on this, for example:
Among the consensus of the commentators, a well-known commentary says that the term /ahqab/, in this text, means that 'some long spaces of time will pass one after another without having an end; with each one that passes, another substitutes'.
In some traditions, it is said that this verse is about those evildoers who will finally be free from the fire, not about those who will be in Hell forever. 
Then, to point to a small part of the great punishments in Hell, it says: "Nothing cool shall they taste therein, nor any drink".
"Except a boiling fluid, and pus".
And also, of course, the thick hot smoke mentioned in Sura Waqiah No. 56, verse 43 thus: "And in the shades of Black Smoke".
The term /hamim/ means 'a boiling water' and the term /qassaq/ means 'pus' flowing from a wound or sore, and some have commented on it to mean 'bad-smelling fluids'.
The Righteous, in contrast with them, drink the wholesome pure drinks from the heavenly springs gifted by Allah: "...and their Lord will give them to drink a Drink, Pure and Holy", (Sura Insan, No. 76, verse 21). And there are some drinks for them, in nice heavenly containers, which are sealed with musk: "Whose seal is musk...", (Sura Mutaffifin, No. 83, verse 26). What a contrast between the righteous and evildoers!
Since these grave and dreadful punishments may seem surprising to some, in addition to this, it says: "A fitting recompense (for their evil)". And why not? Those who were cruel to the oppressed, in the world, and had no mercy on anyone; tyrannical branding all the hearts and spirits so that it seemed that they burnt their victims, violently, deserve to suffer painful punishments like that and their drinks should, also, be so.
Basically, as we have mentioned repeatedly, it is understood from the verses, of the Qur'an, that at least many of the chastisements in the Hereafter are the incarnation of men's deeds in this world. For instance, Sura Tahrim No. 66, verse 7 says: "O you Unbelievers! Make no excuses this Day! You are being but requited for all that you did!" (And now you see them in front of you).
To explain the cause of these punishments, it says: "Surely they used no' to look forward to the Reckoning (for their deeds)".
And the same carelessness paid to the Reckoning and the Day of Judgment was the cause of their rebellion, tyranny, and cruelty, which resulted in this dreadful destiny for them.
In fact, the lack of Faith, about the Reckoning, is a certain cause of rebellion; that which is the cause of those grave chastisements.
The term /layarjun/ is derived from /raja'/ which means both 'hope' and lack of fear and terror'. In principle, when one hopes and expects a penalty, naturally he fears, and if he does not expect it, he does not dread it, and these two correlate with each other. Then, those who do not have hope in the Reckoning do not fear, either.
The term /inna/ shows emphasis; the term /kanu/ is a sign for the past continuous tense; the term / hisaba/ which has been used in an indefinite form, here, after the negative sign of /la/, means 'reckoning' and in general, all point to the fact that they, the transgressors, never expected any Reckoning or the Record, at all. Or, in other words, they had forgotten about the Day of Judgment and they left no room for it in their lives. It is natural that such persons who become the doers of any great evil and sin will finally be involved in these painful punishments.
"And they rejected Our Signs with strong denial".
Their low desires had become so strong in them that they denied all the Signs of Allah in order to continue going astray and accomplish their unlawful wishes.
It is obvious that these verses carry some broad meanings, so that they include the verses consisting of the unity of Allah, prophecy, divine legislation, creation, the prophets miracles, precepts, and traditions And, regarding the denial of the extensive Divine Signs and evidences, that have covered the world of creation and divine legislation, we should accept the punishment for these people as 'a fitting recompense' and just penalty.
Then, as a warning to these rebels and, also, for the emphasis on
the balance of 'sin' and 'penalty', and the authority of a fitting recompense (for their evil), it says: "And everything have We recorded in a book".
We accept this warning so that we, therefore, would not imagine that something of our deeds will be left unrecorded and that we will not
be punished for it, and also, that we would never consider the painful punishments as unjust.
Many of the verses, of the Qur'an, certify the fact that all of Man's deeds, irrespective of small or great, apparent or hidden, and even intentions and beliefs, are recorded.
Once it says: "All that they do is noted in (their) Books (of Deeds)": "Every matter, small and great, is on record", ( Sura Qamar, No. 54, verses 52-53).
Another time it says: "...Verily, Our messengers record all the plots that you make!" (Sura Yunus, No. 10, verse 21)
In addition, it says: "...and We record that which they send before and that which they leave behind..." (Sura Yasin, No. 36, verse 12)
And then, when the records of the evildoers will be handed to them, they will cry saying: "Ah! Woe to us! What a book is this! It leaves out nothing small or great, hut takes account thereof!" (Sura Kahf, No. 18, verse 49).
Undoubtedly, the person who believes in this fact with all his heart, will be very careful in his deeds and the very belief creates a lofty wall between him and sin and is counted as one of the important factors, effective in good training.
In the last verse, of this portion under discussion, the style of speaking is changed from the third person to the second person, addressing them directly and in a threatening tone: "So taste you (the fruit of your deeds); for no increase shall We grant you, but in punishment".
Whatever you cry, whenever you say 'Ah woe to us', or ask to return to the world to do good instead of evil; all are in vain and you gain nothing, but your punishment.
This is the penalty of those who, when they were faced with the Prophets' kind invitation to faith and piety, used to say: "It is the same to us whether you admonish us or be not among (our) admonishers!" (Sura Shuara, No. 26, verse 136).
And again, this is the penalty of those who, when the messages of Allah, are recited get nothing from it: "... but it only increases their flight (from the Truth)!" ( Sura Bani Israil, No. 17, verse 41).
And finally, this is the penalty of those who avoided no sin and were fond of no act of charity.
It is narrated that the Prophet (p.b.u.h.) said: "This verse is the most intensive one in the Qur'an about those who deserve Hell".
Why shouldn't it be so!? When the Merciful and Beneficent Allah addresses them with wrath and says: "...for no increase shall We grant you, but in punishment", to make them completely hopeless.
 Tafsir-i-Nur-uth-Thaqalayn, vol. 5, p 494, Tradition 23 and p. 495, Tradition 26
 Tafsir-i-Kashshaf, vol. 4,
p.690 and Ruh al-Bayan, vol. 10, p. 307