Tafsir of Al-Mutaffifeen 83:7

"Nay" is a refutation of what they were upon regarding under-measuring and heedlessness of the Resurrection and the Reckoning. "Indeed the record of the wicked is in Sijjin," etc., is an explanation for the refutation, or for the obligation to refrain, by way of verification.

"Record" (Kitab) is said to mean "what is written," i.e., what is written of the deeds of the wicked is in..., etc. It is also said to be an infinitive in the sense of "writing," and there is an implicit genitive construction in the speech, i.e., "the writing of the deeds of the wicked is in...," etc. The intended meaning of "the wicked" (al-fujjar) here, according to Abu Hayyan, is the disbelievers. According to more than one scholar, it is a term that encompasses them and the corrupt (al-fasaqah), thus including the under-measurers (al-mutaffifin).

"Sijjin" is said to be [a proper noun] like sikkir. More than one scholar has chosen the view that it is a proper name for a comprehensive book—a register of evil—in which the deeds of the wicked from the two burdened classes (mankind and jinn) are recorded, as Allah the Exalted said...