29. "(On that Day it will be said unto them:) Depart you to that which
you used to deny."
30. "Depart to a shadow failing threefold, (stifling smoke from fire)".
31. "(Which yields) no relief nor shelter from the flame".
32. "Indeed it throws about sparks (as big) as castles;".
33. "As if there were (a string of) yellow camels (marching swiftly)".
34. "Ah woe, that Day, to the Rejecters of Truth."
35. "This is a day wherein they speak not, (they will not be in a
position to put forward any valid defense or plea)",
36. "Nor will it be open to them to put forth excuses".
37. "Ah woe, that Day, to the Rejecters of Truth".
38. "This is the Day of Sorting out (right from wrong). We have brought
you and the men of old together".
39. "If you have a trick (to flee away prom punishment) use it against
40. "Ah woe, that Day, to the Rejecters of Truth".
They Can Neither Defend Themselves Nor Escape.
The final fate of the rejecters of the Hereafter and the Divine Judgment is stated in these verses: a statement that takes one into deep thought, indeed, because it makes clear the horrors of the Event. The command is:
"(On that Day it will be said unto them): Depart you to that which
you used to deny".
Depart to the blazing fire (Hell) which you used to mock. Depart to the different kinds of punishment which you have prepared for yourselves in your previous life.
The term /intaliqu/ is based on /intilaq/ which means: 'to depart, go one's way without stopping, to be free or loose'.
In fact, it is an explanation of their state in the Hereafter. They will be kept a long time for their account, then, being given leave, they will be told to go to Hell promptly without any pause.
The presenter of the case may be Allah, Who commands them directly of the punishment to come, or it may be the angels. The tone of the statement is quite harsh, which is also a kind of torment.
"Depart to a shadow falling threefold, (stifling smoke from fire)".
A column of smoke falls from above, another from the right side, and the third one from the left side. This black and thick hostile smoke surrounds them to envelop them completely
This shadow gives no comfort, nor coolness, since they themselves are from fire, so it says:
"(Which yields) no relief, nor shelter from the flame".
Some persons may think that a shadow is there which partly reduces the heat of the flames of the fire, but this verse conveys the contrary idea. It suggests that this shadow is not of the kind that you think of, but it is a hot stifling one rising from the thick smoke of fire that reflects the heat of flames, totally.
Sura Waqiah, No. 56, verses 41-44 attest to the mentioned subject and refer to the companions of the Left Hand:
"The Companions of the Left Hand - What will be the Companions of the Left Hand?". "(They will be) in the midst of a fierce Blast of Fire and in Boiling Water," "And in the shades of Black Smoke." "Nothing (will there be) to refresh, nor to please:"
It has been said that the threefold shadow denotes a reflection of their present triple rejection to the principles of religion, i.e. monotheism, prophecy, and Resurrection; because, rejection of the Resurrection is not separate from the rejection of the other two.
But some others have said that it refers to the triple source of their faculties of anger, carnality, and suspicion. The triple shadows of smoke illustrate the black stains of sins.
The following is the translation of a Persian poem:
Keep away from anger and carnality.
The smoke of which darkens the insight.
When anger appears, wisdom disappears:
And when lust dominates, the soul is impudent.
"Indeed it throws about sparks (as big) as castles",
They are not like the sparks thrown off by a fire in our human world, which are sometimes very tiny.
The term /qasr/ 'castle' is meaningfully used here. Perhaps, it is more suitable to say: 'spark like the mountains'. But it should not be forgotten that, as it was mentioned for the verses before, mountains are the origin of many blessings as well as the headsprings of the wholesome sweet water, while castles of the oppressors are the source of blazing hot fire.
The next verse conveys another form of descriptive explanation for the sparks of this blazing fire: "As if there were (a string of) yellow camels (marching swiftly)."
The term /jimalah/ 'camels' is a plural form of /jamal/ 'camel', and the word /sufr/ is a plural form of /asfar/ which means: 'that which is yellow' because sparks of fire are usually a reddish yellow.
In the former verse the sparks, from the point of view of size, were likened to castles and in this verse, from the point of view of number, colour, and speed, they are likened to a number of yellow marching camels.
When the sparks are so, it is obvious what the blazing fire is! And, besides this, how many other punishments are there nearby?
O Lord Please protect all of us against it with Your Mercy.
At the end of this portion, once more, the same refrain is repeated: "Ah woe, that Day, to the Rejecters of Truth".
Then another explanation about the characteristics of that terrible Day begins. It says: "This is a day wherein they speak not, (they will not be in a position to put forward any valid defense or plea)".
Yes, it is true that on that Day the sinners will be dumbfounded. This fact is also mentioned in Sura Yasin, No. 36, verse 65: "That Day shall We set a seal on their mouths...". And, also at the end of the same verse it says: "..But their hands will speak to Us, and their feet will bear witness to all that they did". And even more, in some other verses it is said that their skins will speak and bear witness to what should be said.
"Nor will it be open to them to put forth excuses".
They are allowed neither to say anything nor to excuse and defend, because the facts will speak plainly enough, against them, and they do not need to speak. In the human world, this prevaricating tongue misused its freedom: falsely denied the prophets, mocked the righteous, canceled the right, and substituted the wrong in place of the right. So, in the spiritual world this tongue should be locked and shut as a punishment. The very state is a torment, too, because one cannot defend or excuse oneself.
There is a narration from Imam Sadiq (p.b.u.h.) in which he says: "Allah is greater and more just than not to allow His servant to apologize to Him with his plausible excuse. But they have no plausible excuse, indeed, to bring up." 
From some of the verses, of course, it is understood that sinners can speak sometimes in the Hereafter, since, there are many halting places, therein, where some of their tongues are shut and their limbs bear witness, and in some others, their tongues are allowed to express their intensive begrudging, grief, and disaster.
Again it says: "Ah woe, that Day, to the Rejecters of Truth".
Next, the sinners are addressed. To describe 'that Day', it says: "This is the Day of Sorting out (right from wrong). We have brought you and the men of old together".
All members of the human race, from the earliest ones to the latest, with no exception, are gathered for reckoning and the Great Judgment
"If you have a trick (to flee away from punishment) use it against Me!"
Can you escape from My domain?
Or, are you able to defeat My Power?
Or, can you ransom and redeem yourself?
Or, are you able to deceive the Accountants?
Do your best, but do know that you can do nothing.
In fact, this is a term used to show their inability and helplessness; the same demand as that which is made for the Holy Qur'an as we can see in Sura Baqarah No. 2. verse 23: "And if you are in doubt as to what We have revealed (from time to time) to Our servant, then produce a Sura like it..."
As Raqib says in Mufradat: /kayd/ means 'applying or thinking of a remedy,' which is sometimes blameworthy and sometimes praiseworthy, though the former is more frequently used (as it is used in the above verse).'
On that Day, certainly, they can do nothing because, as we know, there is no means for Man, of any kind, to use for his defense, which Sura Baqarah, No. 2. verse 166, points out: "...and all relations between them would be cut off."
It is interesting to note that, on the one hand, that Day is called 'the Day of Sorting out' and, on the other hand, it is said that: "We have brought you and the men of old together"; both occurring in the same section. At first, all are gathered in the Great Court of Justice, then they are divided into different rows in accordance with their belief and their deeds. Even those who go to Paradise, having different rows of different degrees; the likes of which are those who go to Hell, having different rows with various steps of descent.
Yes, that Day is the day of sorting out (right from wrong, and oppressor from oppressed).
Again, the warning and enlightening verse is repeated: "Ah woe, that Day, to the Rejecters of Truth".
 Nur uth-Thaqalayn, vol. 5, p. 49.