Kings III 22:30

30 And the king of Israel said to Josaphat king of Juda, I will disguise myself, and enter into the battle, and do thou put on my raiment. So the king of Israel disguised himself, and went into the battle.

Kings III 22:30 In-Context

28 And Michaias said, If thou return at all in peace, the Lord has not spoken by me.
29 So the king of Israel went up, and Josaphat king of Juda with him to Remmath Galaad.
30 And the king of Israel said to Josaphat king of Juda, I will disguise myself, and enter into the battle, and do thou put on my raiment. So the king of Israel disguised himself, and went into the battle.
31 And the king of Syria had charged the thirty-two captains of his chariots, saying, Fight not small or great, but against the king of Israel only.
32 And it came to pass, when the captains of the chariots saw Josaphat king of Juda, that they said, this seems the king of Israel. And they compassed him about to fight him; and Josaphat cried out.

The Brenton translation of the Septuagint is in the public domain.