Why Children & Women Of Banu Qurayza Were Enslaved?
Banu Quriaza was a tribe, and every person was involved and agree with their collective decision. If anyone of them disagreed, he or she should have informed the Muslims and declared it at least openly by separating themselves from them. So every sane and adult was punished. Moreover, this was done at the decision of Saad bin Muaaz who was appointed by the Jews themselves to decide their fate. Thirdly, after slaying their men, the only good option for woman and children was left to be taken in the custody of Muslims.