Numbers 18:9, 19

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.

“All the heave offerings of the holy things, which the children of Israel offer to the LORD, I have given to you and your sons and daughters with you as an ordinance forever; it is a covenant of salt forever before the LORD with you and your descendants with you.”