1 Chronicles 23:1-9

1 When David was old and full of days, he made his son Solomon king over Israel.
2 David assembled all the leaders of Israel and the priests and the Levites.
3 The Levites, thirty years old and upward, were counted, and the total was thirty-eight thousand.
4 "Twenty-four thousand of these," David said, "shall have charge of the work in the house of the Lord, six thousand shall be officers and judges
5 four thousand gatekeepers, and four thousand shall offer praises to the Lord with the instruments that I have made for praise."
6 And David organized them in divisions corresponding to the sons of Levi: Gershon, Kohath, and Merari.
7 The sons of Gershon were Ladan and Shimei.
8 The sons of Ladan: Jehiel the chief, Zetham, and Joel, three.
9 The sons of Shimei: Shelomoth, Haziel, and Haran, three. These were the heads of families of Ladan.