Numbers 8:22-24

Darby Translation

²² And afterwards the Levites came in to perform their service in the tent of meeting before Aaron, and before his sons; as Jehovah had commanded Moses concerning the Levites, so did they to them.

²³ And Jehovah spoke to Moses, saying,

²⁴ This is that which concerneth the Levites: from twenty-five years old and upward shall he come to labour in the work of the service of the tent of meeting.