Leviticus 7:33-34

33He of the sons of Aaron that presenteth the blood of the peace-offerings, and the fat, shall have the right shoulder for [his] part.

34For the breast of the wave-offering, and the shoulder of the heave-offering, have I taken of the children of Israel from the sacrifices of their peace-offerings, and have given them unto Aaron the priest and unto his sons from the children of Israel by an everlasting statute.