1 Chronicles 23:2-6
2And he gathered together all the leaders of Israel with the priests and the Levites.
The Work of the Levites
3aAnd the Levites were numbered from thirty years old and upward, and btheir number by 1census of men was 38,000. 4Of these, 24,000 were ato direct the work of the house of Yahweh; and 6,000 were bofficers and judges, 5and 4,000 were gatekeepers, and a4,000 were praising Yahweh with the instruments which 1David made for giving praise. 6And David divided them into divisions aaccording to the sons of Levi: Gershon, Kohath, and Merari.