This was the ordering of them in their service, to come into the house of Jehovah according to the ordinance (given) unto them by Aaron their father, as Jehovah, the God of Israel, had commanded him.
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.