Tafsir of Ash-Shams 91:9

His saying, the Exalted: "Indeed, he succeeds who purifies it" is the response to the oath, according to what the group (of scholars) recorded from Qatadah, and Az-Zajjaj and others adhered to this view. The omission of the lam (the affirmative particle) is frequent, especially when the speech requires brevity or when the context serves its function. The doer of "purified" (zakkaha) is the pronoun referring to "who" (man), and the accusative pronoun refers to the soul (al-nafs), and likewise in...