Numbers 25:13

25:13 So it will be to him and his descendants after him a covenant of a permanent priesthood, because he has been zealous for his God, and has made atonement for the Israelites.’”

Numbers 18:1

Responsibilities of the Priests

18:1 The Lord said to Aaron, “You and your sons and your tribe with you must bear the iniquity of the sanctuary, and you and your sons with you must bear the iniquity of your priesthood.