2 Chronicles 20:1-2, 22-23

Some time later the Moabites and Ammonites, accompanied by Meunites, joined forces to make war on Jehoshaphat. Jehoshaphat received this intelligence report: “A huge force is on its way from beyond the Dead Sea to fight you. There’s no time to waste—they’re already at Hazazon Tamar, the oasis of En Gedi.”

As soon as they started shouting and praising, GOD set ambushes against the men of Ammon, Moab, and Mount Seir as they were attacking Judah, and they all ended up dead. The Ammonites and Moabites mistakenly attacked those from Mount Seir and massacred them. Then, further confused, they went at each other, and all ended up killed.