2 Chronicles (Author Compiled by Isaiah and Ezra from records of Nathan, Gad, Iddo, Ahijah, Jehu and others.)
18:29And the king of Israel said to Jehoshaphat, I will disguise myself, and will enter into the battle; but put thou on thy robes. And the king of Israel disguised himself; and they went into the battle.
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.