Numbers 18:8-12

Then the LORD spoke to Aaron, “Look, I have put you in charge of the contributions  brought to me. As for all the holy offerings  of the Israelites, I have given them to you and your sons as a portion and a permanent statute.  A portion of the holiest offerings kept from the fire will be yours; every one of their offerings that they give me, whether the grain offering, sin offering, or guilt offering will be most holy for you and your sons. You are to eat it as a most holy offering.  Every male may eat it; it is to be holy to you. “The contribution of their gifts also belongs to you. I have given all the Israelites’ presentation offerings  to you and to your sons and daughters as a permanent statute.  Every ceremonially clean person in your house may eat it. I am giving you all the best of the fresh oil, new wine, and grain,  which the Israelites give to the LORD as their firstfruits.