This was from the "What Happened to Banu Quraytha" talk page.
At noon of the same day Gabriel came to the apostle, wearing a silken turban and riding on a mule saddled with brocade. He said, 'Hast thou put away thy arms, apostle of Allah?' He replied, 'Yes', and Gabriel said, 'But the angels have not yet put away theirs. I have come here to call the people to follow the command of Allah and march against the Banu Qurayza. I go myself to make them tremble.' Therefore the apostle of Allah ordered it to be proclaimed that none should hold afternoon prayers until they reached the Jewish stronghold. So in fact contrary to mohammedan claims, Mohammed was order to ride out against the Banu Qurayza without any provocation, it was "Allah's (or Gabriël's) call".
The apostle sent Ali ahead with his standard and the people hastened to join it. When Ali reached the fort he heard language offensive to Islam and returned to meet the apostle, whom he warned not to approach the Qurayza. 'Why?' asked the apostle. 'Didst thou hear them insult me? Had they seen me there, they would not have spoken thus.' When he arrived in the territory of Qurayza he alighted near the Well of Ana and the people assembled around him. Many arrived after the last evening prayers without having held their afternoon prayers, so they held their afternoon prayers after the last evening prayers; but Allah did not punish them for that nor did the apostle of Allah reproach them. So in fact language offensive to islam was enough to provoke what will follow?
The apostle of Allah besieged the Qurayza for twenty‑five days until they were distressed, and Allah struck fear into their hearts. A twenty five day siege of their city but this was not all to come
When they had become convinced that the apostle would not depart until he had humbled them, Kab, their chief, spoke to them thus. I have three suggestions to make, of which you may select whichever you prefer. We can obey this man and believe in him; for it is plain that he is an inspired prophet. Notice the mohammedan bias, why would these jews acknowledge Mohammed was a prophet of god, yet not follow him but rather their own scriptures?
In this case, your lives, property and children will be secure.' They replied, 'We shall never abandon the commandments of the Torah, nor substitute any others for them.' He went on, 'If you reject this, we can kill our children and women, and go out to Muhammad and his companions with drawn swords; then God will decide between us and Muhammad. If we perish, we shall perish without leaving orphans who might suffer evil, but if we are victorious, I swear we shall take their wives and their children!' They rejoined, 'Should we kill these poor creatures? What would life be to us without them?' He said, 'If you reject this, too, then consider. This is the Sabbath night, and it is possible that Muhammad thinks he is secure. Let us therefore make a sortie, and we may surprise him and his men.' But they answered, 'Shall we desecrate the Sabbath, and do on the Sabbath what none has done before save those who were afterwards transformed into apes?' Kab said at last, 'Not a man of you has, from the time his mother gave him birth, been able to hold firm to a decision for even one single night’
Then the Qurayza asked the apostle to send them Abu Lubaba ‑ one of the Aus, to which tribe they had been allied ‑that they might consult with him. When he arrived the men rose, and the women and children crowded around him in tears, so that he was deeply touched. They said, 'Think you that we ought to leave the fort as Muhammad commands?' and although he said 'Yes', he drew his hand across his throat, to show that they would be slaughtered.
Abu Lubaba said afterwards, 'By Allah! I had scarcely left them before I realized that I had betrayed Allah and His apostle! When Abu Lubaba departed he did not go to the apostle of Allah, but tied himself to one of the pillars of the mosque, saying, 'I shall not stir from this place until Allah pardons me for what I have done', and he swore by Allah that he would never tread the soil of the Banu Qurayza nor be seen again in the country where he had acted treacherously towards Allah and His apostle. When the apostle of Allah heard of this, he said, 'Had he come to me, I would have interceded for him; but as he has acted in this way, 1 will not deliver him until Allah pardons him. Abu Lubaba remained tied six days; whenever the hour for prayers arrived, his wife came and untied him that he might make his devotions. Afterwards she again bound him to the post.
In the morning the Qurayza came down from their fort to surrender to the apostle of Allah, and the Aus begged that ‑ as the apostle had dealt leniently with allies of the Khazraj ‑ he would do the same for the allies of the Aus. The apostle said, 'Would you like one of your own people to decide their fate’ and they welcomed it. He continued, 'Then let Sad b. Muadh decide.' Sad had been struck by an arrow in the defence of the Ditch, so his people mounted him on a donkey ‑ with a leather pillow under him, for he was a stout and handsome man ‑ and brought him to the apostle. They told him, 'Deal kindly with thy allies, because the apostle of Allah has appointed thee for this purpose.' But they entreated him too much and he said, 'Sad will take good care not to incur the censure of Allah by fearing the censure of men.' Then some of his people went away and lamented for the men of the Banu Qurayza, before Sad even reached them, because Sad had spoken thus.
When Sad appeared the apostle said to the Muslims, 'Arise in honour of your chief!” Then Sad asked, 'Do you covenant with Allah to abide by my decision?' and they said, 'We do!’ The apostle of Allah also replied, 'Yes.' And Sad pronounced the following sentence, 'I decree that the men be killed, the property be divided, and the women with their children be made captives.' The apostle of Allah said, 'Thou hast decided according to the will of Allah, above the seven firmaments.'
The apostle of Allah imprisoned the Qurayza in Medina while trenches were dug in the market‑place. Then he sent for the men and had their heads struck off so that they fell in the trenches. They were brought out in groups, and among them was Kab, the chief of the tribe. In number, they amounted to six or seven hundred, although some state it to have been eight or nine hundred. All were executed. One man turned to his people and said, 'It matters not! By God's will, the children of Israel were destined for this massacre!’ Then he seated himself and his head was struck off.
Aisha, the wife of the apostle, said, 'Only one of their women was killed. By Allah! She was with me, talking and laughing, while the apostle slaughtered her countrymen in the marketplace; and when her name was called, I asked, "What is this for?" and she replied, "I am going to be slain!" I asked why and she answered, "For something I have done!" Then she was taken away, and her head was struck off. But I shall never cease to marvel at her good humour and laughter, although she knew that she was to die." She was the woman who threw a millstone down from the Qurayza fort and killed a Believer.
Now the apostle distributed the property of the Banu Qurayza, as well as their women and children, to the Muslims, reserving one‑fifth for himself. Every horseman received three shares, one for himself and two for his steed, and every foot soldier one share. There were thirty‑six horses present on the day of the Qurayza. The apostle dispatched an emissary to Najd with the prisoners, to barter them as slaves in exchange for horses and camels.
The apostle of Allah selected one of the Jewish women, Rayhana, for himself, and she remained with him as his slave until she died. He had suggested marriage to her, that she should wear the veil (to separate her from all other persons, as his wives did), but she replied, 'Rather allow me to remain thy slave; it will be more easy for me, and for thee.' At the time of her capture she was an enemy of Islam, and desired to remain a Jewess; so the apostle was sad and stayed aloof from her. Then one day, while he was sitting with his companions, he heard the sound of sandals behind him, and said, 'This is one who comes to inform me that Rayhana has made profession of Islam.' It was indeed so, which pleased him greatly. After the Qurayza had been slain, and their possessions dispersed, the wound of Sad opened again and he died a martyr. In the middle of the night Gabriel, wearing a turban of gold brocade, came to the apostle, and asked, 'Who is this dead man for whom the gates of heaven stand ajar and for whom the throne quivers with joy?' At this, the apostle rose in haste and went to Sad, but he found him dead.
Sad was a corpulent man, but when the people carried him to be buried they found him light. And some said, 'Though he is stout, we never bore a lighter corpse than his.' When this came to the hearing of the apostle of Allah, he explained, 'Sad had other bearers besides you, and I swear by Him who holds my life in His hands that the angels bore the soul of Sad, and the heavenly throne shook for him.