2 Kings (Author Compiled by Isaiah and Jeremiah from records of Nathan, Gad, Iddo, Ahijah, Jehu and others.)
11:5And he commanded them, saying, This is the thing that ye shall do; A third part of you that enter in on the sabbath shall even be keepers of the watch of the king's house;
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.