Numbers 8:24 KJV
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:
Numbers 8:24, King James Version
In context
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:
25 And from the age of fifty years they shall cease waiting upon the service thereof, and shall serve no more: