Numbers 8:22-24

King James Version

²² And after that went the Levites in to do their service in the tabernacle of the congregation before Aaron, and before his sons: as the Lord had commanded Moses concerning the Levites, so did they unto them.

²³ And the Lord spake unto Moses, saying,

²⁴ This is it that belongeth unto the Levites: from twenty and five years old and upward they shall go in to wait upon the service of the tabernacle of the congregation: