Numbers 18:3-9

³They shall keep your commands and the duty of the whole Tent; only they shall not come near to the vessels of the sanctuary and to the altar, that they not die, neither they nor you.

⁴They shall be joined to you and keep the responsibility of the Tent of Meeting, for all the service of the Tent. A stranger shall not come near to you.

⁵“You shall perform the duty of the sanctuary and the duty of the altar, that there be no more wrath on the children of Israel.

⁶Behold, I myself have taken your brothers the Levites from among the children of Israel. They are a gift to you, dedicated to the LORD, to do the service of the Tent of Meeting.

⁷You 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.”

⁸The 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.

⁹This 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 render to me, shall be most holy for you and for your sons.