Numbers 18:4

1 The LORD said to Aaron, “You and your sons and your fathers’ house with you shall bear the iniquity of the sanctuary; and you and your sons with you shall bear the iniquity of your priesthood.

2 Bring your brothers also, the tribe of Levi, the tribe of your father, near with you, that they may be joined to you, and minister to you; but you and your sons with you shall be before the Tent of the Testimony.

3 They 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.

4 They 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.

6 Behold, 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.

7 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.”