Ambrose of Milan, on Num 17:8

“He returned on the following day, and found that the rod of Aaron for the house of Levi, was budded: and that the buds swelling it had bloomed blossoms, which spreading the leaves, were formed into almonds.”

“And so He Himself also chose Aaron as priest, that not the will of man but the grace of God should have the chief part in the election of the priest; not the voluntary offering of himself, nor the taking it upon himself, but the vocation from heaven, that he should offer gifts for sins who could be touched for those who sinned, for He Himself, it is said, bears our weakness. No one ought to take this honour upon himself but they are called of God, as was Aaron, and so Christ did not demand but received the priesthood.”

Imported from an open dataset — not yet checked against the printed edition.