Numbers 18:8, 19

Then the LORD said to Aaron, “I myself make you responsible for the offerings given to me. All the holy offerings that the Israelites give to me, I give to you and your sons as your share, your continual portion.

Anything the Israelites present as holy gifts I, the LORD, give to you, your sons and daughters as your continual portion. This is a lasting agreement of salt before the LORD for you and your children forever.”