Numbers 8:24 in the King James Version
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:
Context
23 The LORD spoke to Moses, saying,
24 “This is what is assigned to the Levites: from twenty-five years old and upward they shall go in to wait on the service in the work of the Tent of Meeting;
25 and from the age of fifty years they shall retire from doing the work, and shall serve no more,