Numbers 8:9
And thou shalt bring the Levites before the tabernacle of the congregation: and thou shalt gather the whole assembly of the children of Israel together: And thou shalt bring the Levites before the tabernacle of the congregation: and thou shalt gather the whole assembly of the children of Israel together:
Numbers 8:9 is the gathering for the consecration of the Levites, with the Levites brought before the tabernacle of the congregation and the whole assembly of Israel brought together for that purpose. The consecration so gathered for was completed by the people laying their hands upon the Levites, by Aaron presenting the Levites to the Lord as an offering from Israel, and by sacrifices. The Levites thus consecrated served in the sanctuary under the priests, yet they did not themselves hold the priestly office.