Fussilat: (46) Whoever does righteousness...

(Whoever does righteousness) — that is, by believing in the scriptures and acting according to their requirements — (then it is for himself) — meaning, it is for his own self that he performs it, or that its benefit is for him and not for another. Both the conditional (shartiyyah) and the relative (mawsuliyyah) interpretations are valid for "whoever" (man), and likewise in His saying, Exalted is He, (and whoever does evil, then it is against himself) — meaning its harm is against him, not against another — (and your Lord is never unjust to His servants).

(46)

This is a concluding parenthetical clause (i'tirad tadh-yili) that reinforces the content of what preceded it. It is built upon the premise that refraining from rewarding the righteous for their deeds, or rewarding one person for the deeds of another, or punishing someone without an offense—or for the offense of another—is considered akin to the injustice that is impossible to originate from Him, the Exalted. Some have not found it necessary to employ such a premise; the discussion regarding this, and regarding the interpretation of the negation and the hyperbole (mubalaghah), has already passed, so recall it.