Numbers 18:2-7

2Also 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.

3They 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.

4They 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.

5And 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.

6Behold, I Myself have taken your brethren the Levites from among the children of Israel; they are a gift to you, given by the Lord, to do the work of the tabernacle of meeting.

7Therefore you and your sons with you shall attend to your priesthood for everything at the altar and behind the veil; and you shall serve. I give your priesthood to you as a gift for service, but the outsider who comes near shall be put to death.”