Numbers 18:9, 19

Of all the most holy offerings reserved from the fire this will be yours: Every offering of theirs, whether from every grain offering or from every purification offering or from every reparation offering which they bring to me, will be most holy for you and for your sons.

All the raised offerings of the holy things that the Israelites offer to the LORD, I have given to you, and to your sons and daughters with you, as a perpetual ordinance. It is a covenant of salt forever before the LORD for you and for your descendants with you.”