Tafsir of Ta-Ha 20:36

(He said, "You have been granted your request, O Moses.")

Meaning: You have been given what you asked for. The word "su'lak" (your request) is used here in the sense of a passive participle (maf'ul), similar to "khubz" (bread) and "akl" (food), meaning "what is baked" and "what is eaten." The granting (i'ta') refers to the attachment of His Will, Exalted is He, to the occurrence of those requests and their realization for him, peace be upon him, as an absolute certainty. His decreeing them was definitive, so they were all already attained for him, even if the occurrence of some of them in actuality was deferred, such as the facilitation of affairs and the strengthening of his back.

It is in consideration of this that it was said: "We will strengthen your arm with your brother." The manifest implication of some traditions suggests that Aaron’s partnership in prophethood—meaning his being made a prophet just as Moses was—occurred at that very moment, even if Moses, peace be upon him, was not with his brother at that time. Ibn Abi Hatim recorded from Ibn Abbas regarding the verse, "And associate him with me in my task," that Aaron was made a prophet at that very hour when Moses was made a prophet, peace be upon them both. His calling out, peace be upon him, is an honor bestowed upon him through direct address, following upon a previous honor.