Numbers 8:6-11
6“Now set the Levites apart from the rest of the people of Israel and make them ceremonially clean.
7Do this by sprinkling them with the water of purification, and have them shave their entire body and wash their clothing. Then they will be ceremonially clean.
8Have them bring a young bull and a grain offering of choice flour moistened with olive oil, along with a second young bull for a sin offering.
9Then assemble the whole community of Israel, and present the Levites at the entrance of the Tabernacle.
10When you present the Levites before the Lord, the people of Israel must lay their hands on them.
11Raising his hands, Aaron must then present the Levites to the Lord as a special offering from the people of Israel, thus dedicating them to the Lord’s service.