2 Chronicles 8:14-15

And he appointed, according to the ordinance of David his father, the courses of the priests to their service, and the Levites to their offices, to praise, and to minister before the priests, as the duty of every day required; the doorkeepers also by their courses at every gate: for so had David the man of God commanded. And they departed not from the commandment of the king unto the priests and Levites concerning any matter, or concerning the treasures.