Numbers 8:24-26

New American Standard Bible

²⁴ “This is what applies to the Levites: from ^(A)twenty-five years old and upward ^[a]they shall enter to perform service in the work of the tent of meeting. ²⁵ But at the age of fifty years they shall ^[b]retire from service in the work and not work anymore. ²⁶ They may, however, ^[c]assist their brothers in the tent of meeting, ^(B)to fulfill an obligation, but they themselves shall do no work. In this way you shall deal with the Levites in their obligations.”