Tafsir of Al-Lail 92:18

{Who gives his wealth}—that is, he bestows and spends it, {purifying himself}—seeking to be pure and flourishing in the sight of Allah, the Exalted, not desiring through it show or reputation, or seeking to purify himself from sins. The sentence is in the accusative case as a circumstantial qualifier (hal) from the pronoun in {yu'ti} (gives).

It is permissible that it is a substitute (badal) for the relative clause (silah), in which case it has no place in grammatical inflection. It is also permissible that the verb alone is a substitute for the previous verb alone. Both these views were challenged on the grounds that a substitute is a category of dependent (tabi')—every second element in it is inflected according to the inflection of its predecessor, and the relative clause has no inflection for a dependent to be established within it. As for the verb, the cause of its inflection—which is the nominative case—is present regardless of its dependency; according to the well-known opinion, this is its detachment from a nasib (accusative particle) or jazim (jussive particle). Thus, it is not inflected according to its predecessor, as this would imply its inflection is due to dependency, whereas here it is not, but rather due to detachment.

It was answered—ignoring what is in that definition [of a substitute], some of which Al-Radi pointed out—regarding the first objection: that the intended meaning is "inflected according to the inflection of its predecessor if it has an inflection," or that it means "to be inflected according to its predecessor both in existence and non-existence." It was also said that applying the term "dependent" to this and similar instances of particles and non-inflected verbs is figurative, in the sense that it resembles a dependent by conforming to its predecessor in what the latter possesses. As for the second [objection]: a thing may be intended for a specific purpose even if it was established prior to that for another reason—such as the alif of duality or the waw of the plural; they are brought to signify duality and plurality, and they are established as such, then the agent of the nominative case comes upon the dual and plural [nouns], and they [the markers] are already present in them beforehand, yet they are intended for it [the case]. Al-Sayyid Isa said: "The intent of their statement 'every second is inflected...' is 'every second that would be inflected if it were not already inflected'—so contemplate and be not heedless."

It is also permissible that {yazakka} is understood with an implied lam of purpose (li-an), as the reason for his giving, where the lam is omitted—the omission of which from an (that) and anna is common—and then an itself is omitted, so the verb is rendered in the nominative or remains in the accusative, as in the saying of Tarafa: O you who rebuke me for attending the battle It has been narrated with the nominative ahdaru and the accusative ahdara. It is said that this is by implying li-an (for that) or 'an an (because I attend), and the same process occurred as you have heard. Regardless, the discourse indicates that the intent behind his "giving" is his spending it in the avenues of righteousness and goodness.

Al-Hasan ibn Ali ibn Al-Hasan ibn Ali ibn Abi Talib—may Allah, the Exalted, be pleased with them all—read it as {yuzzakka} by assimilating the ta into the zay.