John Gill Bible Commentary

And the king of Israel said unto Jehoshaphat, I will disguise myself, and enter into the battle,.... Change his clothes, his royal robes, and put on others, perhaps the habit of a common soldier; having, it may be, been informed by some deserters or spies, of the design of Benhadad against him. Abarbinel thinks the meaning is, that he would clothe himself with a coat of mail, and take to him the each of the instruments of war, and so go into the battle secure; this seems probable from Kg1 22:34 and this he might do to elude the prophecy of Micaiah: but put thou on thy robes; his royal robes, or rather keep them on, that he might appear to be the chief commander of the army. There seems to be a good deal of insincerity and treachery in this conduct of Ahab's, whatever honour he might pretend to Jehoshaphat, or safety he might promise him in such a situation; his view seems to be to save himself at the hazard of the life of Jehoshaphat, especially if the Septuagint version could be established, "and put on my clothes"; which is natural enough, but would have been too barefaced: and the king of Israel disguised himself, and went into the battle; as if he had been a common soldier.