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 which ye shall do: a third part of you, that come in on the sabbath, shall 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.