2 Chronicles 35:15-16

15The singers, the sons of Asaph, were also in their places in accordance with the command of David, Asaph, Heman, and Jeduthun the king’s seer; and the gatekeepers at each gate did not need to leave their service, because their kinsmen the Levites prepared for them.

16So all the service of the Lord was prepared on that day to celebrate the Passover, and to offer burnt offerings on the altar of the Lord, in accordance with the command of King Josiah.