Numbers 18:1-4

¹And the Lord spoke to Aaron, saying, Thou and thy sons and thy father's house shall bear the sins of the holy things, and thou and thy sons shall bear the iniquity of your priesthood.

²And take to thyself thy brethren the tribe of Levi, the family of thy father, and let them be joined to thee, and let them minister to thee; and thou and thy sons with thee shall minister before the tabernacle of witness.

³And they shall keep thy charges, and the charges of the tabernacle; only they shall not approach the holy vessels and the altar, so both they and you shall not die.

⁴And they shall be joined to thee, and shall keep the charges of the tabernacle of witness, in all the services of the tabernacle; and a stranger shall not approach to thee.