2 Chronicles 20:22-23

22 And when they began to sing and praise, the  Lord set a an ambush against the men of b Ammon, Moab, and Mount Seir, who had come against Judah, so that they were routed. 23 For 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, c they all helped to destroy one another.

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