Exodus 29:27-28

29:27 You are to sanctify the breast of the wave offering and the thigh of the contribution, which were waved and lifted up as a contribution from the ram of consecration, from what belongs to Aaron and to his sons. 29:28 It is to belong to Aaron and to his sons from the Israelites, by a perpetual ordinance, for it is a contribution. It is to be a contribution from the Israelites from their peace offerings, their contribution to the Lord.