The Levites: Ceremonies at Consecration of Presenting Them to God As an offering for the People
Source: TTT
Numbers 8:11, 15
Aaron is to present the Levites before the LORD as a wave offering from the sons of Israel, so that they may perform the service of the LORD. / After you have cleansed them and presented them as a wave offering, they may come to serve at the Tent of Meeting.