Numbers 31:13-18

13And Moses, Eleazar the priest, and all the leaders of the congregation went to meet them outside the camp.

14But Moses was angry with the officers of the army—the commanders of thousands and commanders of hundreds—who were returning from the battle. 15“Have you spared all the women?” he asked them. 16“Look, these women caused the sons of Israel, through the counsel of Balaam, to turn unfaithfully against the LORD at Peor, so that the plague struck the congregation of the LORD. 17So now, kill all the boys, as well as every woman who has had relations with a man, 18but spare for yourselves every girl who has never had relations with a man.