1 Chronicles 23:24-28

²⁴These were the sons of Levi according to their fathers’ households, the heads of the fathers’ households of those among them who were counted, in the number of names by their head count, doing the work for the service of the house of the Lord, from twenty years old and upward. ²⁵For David said, “The Lord God of Israel has given rest to His people, and He dwells in Jerusalem forever. ²⁶Also, the Levites will no longer need to carry the tabernacle and all its utensils for its service.” ²⁷For by the last words of David, the sons of Levi were counted from twenty years old and upward. ²⁸For their office is to assist the sons of Aaron with the service of the house of the Lord, in the courtyards and in the chambers, and in the purification of all holy things, and the work of the service of the house of God,