2 Chronicles 35:14-15

14And afterward they prepared for themselves and for the priests, because the priests, the sons of Aaron, were offering the burnt offerings and the fat parts until night; so the Levites prepared for themselves and for the priests, the sons of Aaron.

15The singers, the sons of Asaph, were in their place according to the command of David, and Asaph, and Heman, and Jeduthun the king's seer; and the gatekeepers were at each gate. They did not need to depart from their service, for their brothers the Levites prepared for them.