Matthew Henry on Numbers 31:7-12

The Israelites slew the Kings of Midian. They slew Balaam. God's overruling providence brought him thither, and their just vengeance found him. Had he himself rightly believed what he had said of the happy state of Israel, he would not have thus herded with the enemies of Israel. The Midianites' wicked wiles were Balaam's projects: it was just that he should perish with them, Ho 4:5. They took the women and children captives. They burnt their cities and castles, and returned to the camp.