Tafsir of Maryam 19:53

"And We granted him out of Our mercy"—meaning: for the sake of Our mercy toward him—"his brother"—meaning: the support and assistance of his brother, in response to his supplication in His saying: "And appoint for me a minister from my family, Aaron, my brother." It is not the person himself, peace be upon him, because he was older than Moses in age, and his existence preceded his existence. [The word] "brother" is the object of "We granted."

His saying—the Almighty—"Aaron" is an explanatory appositive for it. And His saying—glory be to Him—"a prophet" is a circumstantial qualifier (hal) for him.

It is permissible for "out of" (min) to be for partition. It is said that, in this case, "his brother" would be an appositive of substitution (badal)—either a part for the whole, the whole for the whole, or substitution of inclusion—for "out of." This has been countered by the fact that if it is a noun synonymous with "a part" (ba'd), it is contrary to the apparent meaning; and if it is a particle (min), then substituting a noun for a particle is something that does not exist in their speech. It is also said that the implied meaning is "We granted him something out of Our mercy," so "his brother" is an appositive of substitution for the implied "something." You know, however, that the apparent [meaning] is that it is an object.