New Defender's Study Bible Notes
8:24 Twenty and five years old. The sons of Kohath (a family of the Levites) should serve in the work of the tabernacle during the period of their lives between ages thirty and fifty (compare Numbers 4:3). The same was true of the Gershonites (Numbers 4:23) and the sons of Merari (Numbers 4:30). Evidently the young Levites began a sort of apprenticeship at age twenty-five, then entered the full responsibilities of service at age thirty, retiring from active tabernacle service at age fifty. Many years later, after the temple had replaced the tabernacle, David changed the entrance age to age twenty (I Chronicles 23:24-27).