2 Chronicles 20:22-24

At the very moment they began to sing and give praise, the LORD caused the armies of Ammon, Moab, and Mount Seir to start fighting among themselves. The armies of Moab and Ammon turned against their allies from Mount Seir and killed every one of them. After they had destroyed the army of Seir, they began attacking each other. So when the army of Judah arrived at the lookout point in the wilderness, all they saw were dead bodies lying on the ground as far as they could see. Not a single one of the enemy had escaped.