Numbers 3:5-10

⁵Then the Lord spoke to Moses, saying, ⁶“Bring the tribe of Levi near and set them before Aaron the priest, that they may serve him. ⁷They shall perform the duties for him and for the whole congregation before the tent of meeting, to do the service of the tabernacle. ⁸They shall also keep all the furnishings of the tent of meeting, along with the duties of the sons of Israel, to do the service of the tabernacle. ⁹You shall thus give the Levites to Aaron and to his sons; they are wholly given to him from among the sons of Israel. ¹⁰So you shall appoint Aaron and his sons that they may keep their priesthood, but the layman who comes near shall be put to death.”