And Moses said unto them, have ye saved all the women alive? Which either had been reported to him, or he concluded, by seeing so many with them; and this question is put, not for information, but by way of reproof, and as chiding them for what they had done; for they might have received orders from him to put them to death, when he sent them out; and if so, there was the more reason to be angry with them; or he might conclude they would have done this of themselves, knowing what instruments of mischief these women had been to Israel.
And Moses said unto them, have ye saved all the women alive? Which either had been reported to him, or he concluded, by seeing so many with them; and this question is put, not for information, but by way of reproof, and as chiding them for what they had done; for they might have received orders from him to put them to death, when he sent them out; and if so, there was the more reason to be angry with them; or he might conclude they would have done this of themselves, knowing what instruments of mischief these women had been to Israel.
Numbers 31:16

num 31:16
num 31:16
num 31:16Behold, these caused the children of Israel, through the counsel of Balaam,.... Who advised the Midianites to send their women into the camp of Israel, and allure them to uncleanness, and so draw them into idolatry, which counsel they followed and it succeeded; for, by this means, they were brought

to commit trespass against the Lord in the matter of Peor; by worshipping Baalpeor, the god of the Moabites and Midianites; whereby they transgressed the commandment of God, which forbid them having and worshipping any other gods besides him, and is a sin highly offensive to him, being greatly derogatory to his honour and glory:

and there was a plague among the congregation of the Lord; for that sin; and in that plague died 24,000 persons, Num 25:9.

And Moses was wroth with the officers of the host--The displeasure of the great leader, though it appears the ebullition of a fierce and sanguinary temper, arose in reality from a pious and enlightened regard to the best interests of Israel. No order had been given for the slaughter of the women, and in ancient war they were commonly reserved for slaves. By their antecedent conduct, however, the Midianitish women had forfeited all claims to mild or merciful treatment; and the sacred character, the avowed object of the war (Num 31:2-3), made their slaughter necessary without any special order. But why "kill every male among the little ones"? It was designed to be a war of extermination, such as God Himself had ordered against the people of Canaan, whom the Midianites equalled in the enormity of their wickedness.