2 Kings (Author Compiled by Isaiah and Jeremiah from records of Nathan, Gad, Iddo, Ahijah, Jehu and others.)
11:5and commandeth them, saying, `This is the thing that ye do; The third of you are going in on the sabbath, and keepers of the charge of the house of the king,
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.