No one is to enter the house of the LORD except the priests and those Levites who serve; they may enter because they are consecrated, but all the people are to obey the requirement of the LORD.

1 Chronicles 23:28
but their duty was to assist the descendants of Aaron with the service of the house of the LORD, being responsible for the courts and chambers, the purification of all the holy things, and the work of the service of the house of God,

2 Chronicles 23:5
a third shall be at the royal palace, and a third at the Foundation Gate, while all the others are in the courtyards of the house of the LORD.

2 Chronicles 23:7
The Levites must surround the king with weapons in hand, and anyone who enters the temple must be put to death. You must stay close to the king wherever he goes."

But let none come into the house of the LORD, save the priests, and they that minister of the Levites; they shall go in, for they are holy: but all the people shall keep the watch of the LORD.