Numbers 18:1-7

1So the Lord said to Aaron, "You and your sons and your father's house with you shall bear iniquity connected with the sanctuary, and you and your sons with you shall bear iniquity connected with your priesthood.

2And with you bring your brothers also, the tribe of Levi, the tribe of your father, that they may join you and minister to you while you and your sons with you are before the tent of the testimony.

3They shall keep guard over you and over the whole tent, but shall not come near to the vessels of the sanctuary or to the altar lest they, and you, die.

4They shall join you and keep guard over the tent of meeting for all the service of the tent, and no outsider shall come near you.

5And you shall keep guard over the sanctuary and over the altar, that there may never again be wrath on the people of Israel.

6And behold, I have taken your brothers the Levites from among the people of Israel. They are a gift to you, given to the Lord, to do the service of the tent of meeting.

7And you and your sons with you shall guard your priesthood for all that concerns the altar and that is within the veil; and you shall serve. I give your priesthood as a gift, and any outsider who comes near shall be put to death."