2 Chronicles (Author Compiled by Isaiah and Ezra from records of Nathan, Gad, Iddo, Ahijah, Jehu and others.)
23:6But let none come into the house of Jehovah except the priests and those of the Levites that do the service; they shall go in, for they are holy; but all the people shall keep the watch of Jehovah.
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.