Numbers 18:8-9

And the LORD spoke to Aaron: “Here, I Myself have also given you charge of My heave offerings, all the holy gifts of the children of Israel; I have given them as a portion to you and your sons, as an ordinance forever. This shall be yours of the most holy things reserved from the fire: every offering of theirs, every grain offering and every sin offering and every trespass offering which they render to Me, shall be most holy for you and your sons.