Numbers 31:17

“Now therefore kill every male among the little ones, etc.] Which they had taken and brought captives, (<043109>Numbers 31:9) and kill every woman that hath known man by lying with him; who might be such, at least many of them, who had lain with Israelitish men; and as the adulterers had been put to death, so now the adulteresses; or they were ordered to, be slain, even all of them, lest they should entice the children of Israel to uncleanness, and so to idolatry again: now these were known to be such, either by conjecture at their age, or rather, through the examination of matrons, unless it can be thought, as it is by some, that it was by divine revelation.”

“The little ones - Which they were forbidden to do to other people, Deu 20:14, except the Canaanites, to whom this people had equaled themselves by their horrid crimes, and therefore it is not strange, nor unjust, that God, the supreme Lord of all mens lives, who as he gives them, so may take them away when he pleaseth, did equal them in the punishment. Every woman - Partly for punishment, because the guilt was general, and though some of them only did prostitute themselves to the Israelites, yet the rest made themselves accessary by their consent or approbation; and partly, for prevention of the like mischief from such an adulterous generation. Numbers 31:20”

“31:17-18 Only young virgin women were to be spared, since they had not participated in the incident at Baal-peor.”

“kill every male: The sword of war should spare women and children, as incapable of resisting; but the sword of justice knows no distinction, except that of guilty or not guilty, or more or less guilty. This was the execution of a righteous sentence upon a guilty nation, in which the women were the greatest criminals; and it may safely be said, that their lives were forfeited by their personal transgressions. With respect to the execution of the male infants, who cannot be supposed to have been guilty, God, the author and supporter of life, who has a right to dispose of it when and how he thinks proper, commanded it; and "shall not the Judge of all the earth do right?" Jdg 21:11, Jdg 21:12…”