Numbers 31:15 (KJV)

And they burnt all their cities wherein they dwelt, and all their goodly castles, with fire.

And they took all the spoil, and all the prey, both of men and of beasts.

And they brought the captives, and the prey, and the spoil, unto Moses, and Eleazar the priest, and unto the congregation of the children of Israel, unto the camp at the plains of Moab, which are by Jordan near Jericho.

And Moses, and Eleazar the priest, and all the princes of the congregation, went forth to meet them without the camp.

And Moses was wroth with the officers of the host, with the captains over thousands, and captains over hundreds, which came from the battle.

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

Now therefore kill every male among the little ones, and kill every woman that hath known man by lying with him.

But all the women children, that have not known a man by lying with him, keep alive for yourselves.

And do ye abide without the camp seven days: whosoever hath killed any person, and whosoever hath touched any slain, purify both yourselves and your captives on the third day, and on the seventh day.

And purify all your raiment, and all that is made of skins, and all work of goats' hair, and all things made of wood.