2 Chronicles 23:6

But let no one come into the house of the Lord but only the priests and those of the Levites who have work to do there; they may go in for they are holy; but the rest of the people are to keep the orders of the Lord.

1 Chronicles 23:28-32

Their place was by the side of the sons of Aaron in all the work of the house of the Lord, in the open spaces and in the rooms, in the making clean of all the holy things, in doing all the work of the house of the Lord,

Treasury of Scripture Knowledge

Summary

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.

They that minister

Bible References

They that minister

1 Chronicles 23:28
Their place was by the side of the sons of Aaron in all the work of the house of the Lord, in the open spaces and in the rooms, in the making clean of all the holy things, in doing all the work of the house of the Lord,

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain