Numbers 31:14-18

14Moses was angry with the officers of the army—the commanders of thousands and commanders of hundreds—who returned from the battle. 15“Have you allowed all the women to live?” he asked them. 16“They were the ones who followed Balaam’s advice and enticed the Israelites to be unfaithful to the Lord in the Peor incident, so that a plague struck the Lord’s people. 17Now kill all the boys. And kill every woman who has slept with a man, 18but save for yourselves every girl who has never slept with a man.