2 Chronicles 23:18-19

18And Jehoiada posted watchmen for the house of the Lord under the direction of the Levitical priests and the Levites whom David had organized to be in charge of the house of the Lord, to offer burnt offerings to the Lord, as it is written in the Law of Moses, with rejoicing and with singing, according to the order of David.

19He stationed the gatekeepers at the gates of the house of the Lord so that no one should enter who was in any way unclean.