1 Chronicles 15:16
15:16 David told the leaders of the Levites to appoint some of their relatives as musicians; they were to play various instruments, including stringed instruments and cymbals, and to sing loudly and joyfully.
1 Chronicles 23:2-6
23:2 David assembled all the leaders of Israel, along with the priests and the Levites.
23:3 The Levites who were thirty years old and up were counted; there were 38,000 men.
23:4 David said, “Of these, 24,000 are to direct the work of the Lord’s temple; 6,000 are to be officials and judges;
23:5 4,000 are to be gatekeepers; and 4,000 are to praise the Lord with the instruments I supplied for worship.”
23:6 David divided them into groups corresponding to the sons of Levi: Gershon, Kohath, and Merari.
1 Chronicles 24:3
24:3 David, Zadok (a descendant of Eleazar), and Ahimelech (a descendant of Ithamar) divided them into groups to carry out their assigned responsibilities.