Numbers [In the desert] 18:2-3

²Bring your brothers also, the tribe of Levi United with, 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.

³They shall keep your orders, and the duty of the whole Tent; only they shall not come near to the utensils of the sanctuary and to the altar, that they not die, neither they, nor you.