Tafsir of Al-Mutaffifeen 83:7

{Nay}: A rebuke to them for what they were engaged in regarding cheating (in weights and measures) and their heedlessness of the mention of the Resurrection and the Reckoning. He alerts them that this is something for which one must repent and feel remorse. He then follows this with a general threat against the wicked (fujjar).

{The record of the wicked}: That which is written of their deeds.

If you ask: God has informed us that the record of the wicked is in Sijjin, and He explained Sijjin as a "written record" (kitab marqum). It is as if it were said: "Indeed, their record is in a written record." What does this mean?

I say: Sijjin is a comprehensive book—a register of evil. God has recorded in it the deeds of the devils, the disbelievers, and the corrupt among both jinn and mankind. It is a "written record," meaning inscribed or marked, such that whoever sees it knows there is no good in it. The meaning is that what is written of the deeds of the wicked is fixed in that register.

It is called Sijjin, a fi‘il form derived from al-sijn (imprisonment and constriction), because it is the cause of imprisonment and constriction in Hell. Or, it is because it is cast—as has been narrated—beneath the seventh earth in a desolate, dark place, which is the dwelling of Iblis and his progeny, as a sign of contempt and degradation for it, so that the accursed devils may witness it, just as the angels brought near witness the register of good.

If you ask: Is Sijjin an adjective or a proper noun?

I say: Rather, it is a proper noun transferred from an adjective, like Hatim. It is fully declinable (munsarif) because it possesses only one cause (for being diptote), which is definiteness.

{Woe, that Day, to the deniers * Who deny the Day of Recompense * And none denies it except every transgressor, sinner * When Our verses are recited to him, he says, "Legends of the former peoples" * Nay, but that which they were earning has rusted upon their hearts * Nay, indeed, from their Lord, that Day, they will be veiled * Then indeed, they will [enter and] burn in Hellfire * Then it will be said, "This is the very thing which you used to deny."}