2 Chronicles 23:18-19

18And Jehoiada appointed the offices of the house of Jehovah under the hand of the priests, the Levites, whom David had set by classes over the house of Jehovah to offer up Jehovah's burnt-offerings, as it is written in the law of Moses, — with rejoicing and with singing according to the directions of David.

19And he set the doorkeepers at the gates of the house of Jehovah, that no one unclean in anything should enter in.