Numbers 18:10

You and your sons with you shall keep your priesthood for everything of the altar, and for that within the veil. You shall serve. I give you the service of the priesthood as a gift. The stranger who comes near shall be put to death.”

The LORD spoke to Aaron, “Behold, I myself have given you the command of my wave offerings, even all the holy things of the children of Israel. I have given them to you by reason of the anointing, and to your sons, as a portion forever.

This shall be yours of the most holy things from the fire: every offering of theirs, even every meal offering of theirs, and every sin offering of theirs, and every trespass offering of theirs, which they shall give to me, shall be most holy for you and for your sons.

“This is yours, too: the wave offering of their gift, even all the wave offerings of the children of Israel. I have given them to you, and to your sons and to your daughters with you, as a portion forever. Everyone who is clean in your house shall eat of it.

“I have given to you all the best of the oil, all the best of the vintage, and of the grain, the first fruits of them which they give to the LORD.

The first-ripe fruits of all that is in their land, which they bring to the LORD, shall be yours. Everyone who is clean in your house shall eat of it.