Thematic Bible: The choir that won a battle by singing

In the morning they got up early and went out to the wilderness of Tekoa. As they were about to go out, Jehoshaphat stood and said, "Hear me, Judah and you inhabitants of Jerusalem. Believe in the Lord your God, and you will be established; believe in His prophets, and you will succeed." Then he consulted with the people and appointed some to sing for the Lord and some to praise the splendor of [His] holiness. When they went out in front of the armed forces, they kept singing: Give thanks to the Lord, for His faithful love endures forever. The moment they began [their] shouts and praises, the Lord set an ambush against the Ammonites, Moabites, and [the inhabitants of] Mount Seir who came [to fight] against Judah, and they were defeated. read more.
The Ammonites and Moabites turned against the inhabitants of Mount Seir and completely annihilated them. When they had finished with the inhabitants of Seir, they helped destroy each other. When Judah came to a place overlooking the wilderness, they looked toward the multitude, and there were corpses lying on the ground; nobody had escaped.