Numbers 18:9, 19

This shall be yours of the most holy things, reserved from the fire: every offering of theirs, every grain offering of theirs and every sin offering of theirs and every guilt offering of theirs, which they render to me, shall be most holy to you and to your sons.

All the holy contributions that the people of Israel present to the LORD I give to you, and to your sons and daughters with you, as a perpetual due. It is a covenant of salt forever before the LORD for you and for your offspring with you.”