2 Chronicles 23:4-6

4This is what you must do. When you priests and Levites come on duty on the Sabbath, a third of you will serve as gatekeepers.

5Another third will go over to the royal palace, and the final third will be at the Foundation Gate. Everyone else should stay in the courtyards of the Lord’s Temple.

6Remember, only the priests and Levites on duty may enter the Temple of the Lord, for they are set apart as holy. The rest of the people must obey the Lord’s instructions and stay outside.