of twenty years] Num. VIII. 24. from twenty five years old they begin to wait upon the service of the Tabernacle. Here David, by new warrant, enters them into the work for the Service of the Temple, at twenty years of age: likely more now being needful for this Service, ver. 27. 2 Chron. XXXI. 17. yet they come not to the full possession and fruition of their Place and Office, till thirty years of age, 1 Chron. XXIII. 3. Num. IV, 3, 4, 7.