2 Chronicles 23:18-19

18Also Jehoiada appointed the oversight of the house of the Lord to the hand of the priests, the Levites, whom David had assigned in the house of the Lord, to offer the burnt offerings of the Lord, as it is written in the Law of Moses, with rejoicing and with singing, as it was established by David.

19And he set the gatekeepers at the gates of the house of the Lord, so that no one who was in any way unclean should enter.