2 Chronicles 20:20-24

20And they rose early in the morning and went out into the wilderness of Tekoa. And when they went out, Jehoshaphat stood and said, "Hear me, Judah and inhabitants of Jerusalem! Believe in the Lord your God, and you will be established; believe his prophets, and you will succeed."

21And when he had taken counsel with the people, he appointed those who were to sing to the Lord and praise him in holy attire, as they went before the army, and say, "Give thanks to the Lord, for his steadfast love endures forever."

22And when they began to sing and praise, the Lord set an ambush against the men of Ammon, Moab, and Mount Seir, who had come against Judah, so that they were routed.

23For the men of Ammon and Moab rose against the inhabitants of Mount Seir, devoting them to destruction, and when they had made an end of the inhabitants of Seir, they all helped to destroy one another.

24When Judah came to the watchtower of the wilderness, they looked toward the horde, and behold, there were dead bodies lying on the ground; none had escaped.