Numbers 8:24

Twenty and five years old and upward -The permanent limit as distinguished from the temporaryNumbers 4:3,Numbers 4:23,Numbers 4:30, though David found it necessary to extend the period of the Levites’ service by causing it to commence at 20 years of age1 Chronicles 23:24-28. This rule continued in force from the time of David downward (compare on2 Chronicles 31:17;Ezra 3:8).