Numbers 31:16

14Moses was angry with the officers of the army, the captains of thousands and the captains of hundreds, who came from the service of the war.

15Moses said to them, “Have you saved all the women alive?

16Behold, these caused the children of Israel, through the counsel of Balaam, to commit trespass against the LORD in the matter of Peor, and so the plague was among the congregation of the LORD.

17Now therefore kill every male among the little ones, and kill every woman who has known man by lying with him.

18But all the girls, who have not known man by lying with him, keep alive for yourselves.