Numbers 8:4-14

4 And this was the workmanship of the lampstand, hammered work of gold; from its base to its flowers, it was hammered work; according to the pattern which the LORD had shown Moses, so he made the lampstand.
5 And the LORD said to Moses,
6 "Take the Levites from among the people of Israel, and cleanse them.
7 And thus you shall do to them, to cleanse them: sprinkle the water of expiation upon them, and let them go with a razor over all their body, and wash their clothes and cleanse themselves.
8 Then let them take a young bull and its cereal offering of fine flour mixed with oil, and you shall take another young bull for a sin offering.
9 And you shall present the Levites before the tent of meeting, and assemble the whole congregation of the people of Israel.
10 When you present the Levites before the LORD, the people of Israel shall lay their hands upon the Levites,
11 and Aaron shall offer the Levites before the LORD as a wave offering from the people of Israel, that it may be theirs to do the service of the LORD.
12 Then the Levites shall lay their hands upon the heads of the bulls; and you 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 And you shall cause the Levites to attend Aaron and his sons, and shall offer them as a wave offering to the LORD.
14 "Thus you shall separate the Levites from among the people of Israel, and the Levites shall be mine.