Leviticus 7:35-38

35This is their rightful share. The special gifts presented to the Lord have been reserved for Aaron and his descendants from the time they were set apart to serve the Lord as priests.

36On the day they were anointed, the Lord commanded the Israelites to give these portions to the priests as their permanent share from generation to generation.”

37These are the instructions for the burnt offering, the grain offering, the sin offering, and the guilt offering, as well as the ordination offering and the peace offering.

38The Lord gave these instructions to Moses on Mount Sinai when he commanded the Israelites to present their offerings to the Lord in the wilderness of Sinai.