Adam Clarke on Exodus 29:25

Thou shalt receive them of their hands - Aaron and his sons are here considered merely as any common persons bringing an offering to God, and not having, as yet, any authority to present it themselves, but through the medium of a priest. Moses, therefore, was now to Aaron and his sons what they were afterwards to the children of Israel; and as the minister of God he now consecrates them to the sacred office, and presents their offerings to Jehovah.