2 Kings 3:23

the kings are surely slain[R.V. destroyed], and they have smitten one another R.V. each man his fellow. The Moabites knew of the contests which had been between Israel and Judah in times past, and might readily fancy that the peace which had been made between Ahab and Jehoshaphat had now been broken through some difference during the expedition. They would also know that the Edomite vassal of Judah was likely to seize the first opportunity to strike a blow for independence. Their own wish too was no doubt father to the thought. Hence their impetuous rush down upon the enemy.