2 Chronicles 35:15 NAS

15 The singers, the sons of Asaph, were also at their stations 1according to the command of David, Asaph, Heman, and Jeduthun the king's seer; and 2the gatekeepers at each gate did not have to depart from their service, because the Levites their brethren prepared for them.

References for 2 Chronicles 35:15