Numbers 8:4-14

4 Now this was how the lampstand was made, out of hammered work of gold. From its base to its flowers, it was hammered work; according to the pattern that the Lord had shown Moses, so he made the lampstand.
5 The Lord spoke to Moses, saying:
6 Take the Levites from among the Israelites and cleanse them.
7 Thus you shall do to them, to cleanse them: sprinkle the water of purification on them, have them shave their whole body with a razor and wash their clothes, and so cleanse themselves.
8 Then let them take a young bull and its grain offering of choice flour mixed with oil, and you shall take another young bull for a sin offering.
9 You shall bring the Levites before the tent of meeting, and assemble the whole congregation of the Israelites.
10 When you bring the Levites before the Lord, the Israelites shall lay their hands on the Levites,
11 and Aaron shall present the Levites before the Lord as an elevation offering from the Israelites, that they may do the service of the Lord.
12 The Levites shall lay their hands on the heads of the bulls, and he shall offer the one for a sin offering and the other for a burnt offering to the Lord, to make atonement for the Levites.
13 Then you shall have the Levites stand before Aaron and his sons, and you shall present them as an elevation offering to the Lord.
14 Thus you shall separate the Levites from among the other Israelites, and the Levites shall be mine.