Numbers 18:1-5

Then the LORD said to Aaron: “You and your sons and your father’s house with you shall bear the iniquity related to the sanctuary, and you and your sons with you shall bear the iniquity associated with your priesthood. Also bring with you your brethren of the tribe of Levi, the tribe of your father, that they may be joined with you and serve you while you and your sons are with you before the tabernacle of witness. They shall attend to your needs and all the needs of the tabernacle; but they shall not come near the articles of the sanctuary and the altar, lest they die—they and you also. They shall be joined with you and attend to the needs of the tabernacle of meeting, for all the work of the tabernacle; but an outsider shall not come near you. And you shall attend to the duties of the sanctuary and the duties of the altar, that there may be no more wrath on the children of Israel.