Why the Punishment Was So Severe

Some lessons from this ghazwah. Why was the punishment so severe? Why were four hundred to nine hundred men slaughtered, and the entire remaining population of women and children enslaved, and the whole wealth taken as booty? Why? Why such a severe punishment?

It can be answered in one word, and that is treason. Banū Qurayẓah were citizens of the Islamic state, and they committed treason, and it is an accepted rule that the punishment should befit the crime: the punishment should be proportionate to the crime. And this crime is so great: they committed treason against the Muslims; they committed treason against the Messenger of Allah. Here we're dealing with the Messenger of Allah; we're dealing with Muḥammad (peace be upon him). You lie to Muḥammad, you betray Muḥammad (peace be upon him)? We're not dealing with a particular head of state or a king; we're dealing with Muḥammad (peace be upon him). He was the head of state, the Messenger, the Seal of the Prophets, the most beloved of the creation of Allah to Allah — and they betray him? They lie to him, they conspire against him. So the punishment can be no less than what Saʿd ibn Muʿādh chose, and that's why the Messenger of Allah (peace be upon him) was happy with it, and he said that this was the ruling of Allah from above seven heavens.

Ibn Kathīr said: "All that was due to their disbelief, their breaking of pacts between themselves and the Messenger of Allah, and their allying themselves with the clans against him. None of that did them any good, and brought the wrath of Allah and His Messenger down upon them: a bad bargain for them in this world and the next." So they received the punishment that they deserved.