Numbers 18:5-7

American Standard Version

⁵ And ye shall keep the charge of the sanctuary, and the charge of the altar; that there be wrath no more upon the children of Israel. ⁶ And I, behold, I have taken your brethren the Levites from among the children of Israel: to you they are a gift, given unto Jehovah, to do the service of the tent of meeting. ⁷ And thou and thy sons with thee shall keep your priesthood for everything of the altar, and for that within the veil; and ye shall serve: I give you the priesthood as a service of gift: and the stranger that cometh nigh shall be put to death.