Numbers 3:8-10

New Revised Standard Version, Anglicised Catholic Edition

⁸ they shall be in charge of all the furnishings of the tent of meeting, and attend to the duties for the Israelites as they do service at the tabernacle. ⁹ You shall give the Levites to Aaron and his descendants; they are unreservedly given to him from among the Israelites. ¹⁰ But you shall make a register of Aaron and his descendants; it is they who shall attend to the priesthood, and any outsider who comes near shall be put to death.