From WikiIslam

Let us see What Happened to Banu Quraytha from the Ibn Ishaq's oldest biography of Mohammed and from Tabari.

Tabari VIII:35/Ishaq:464 “The Jews were made to come down, and Allah’s Messenger imprisoned them. Then the Prophet went out into the marketplace of Medina (it is still its marketplace today), and he had trenches dug in it. He sent for the Jewish men and had them beheaded in those trenches. They were brought out to him in batches. They numbered 800 to 900 boys and men. As they were being taken in small groups to the Prophet, they said to one another, ‘What do you think will be done to us?’ Someone said, ‘Do you not understand. On each occasion do you not see that the summoner never stops? He does not discharge anyone. And that those who are taken away do not come back. By God, it is death!’ The affair continued until the Messenger of Allah had finished with them all.”

Ishaq:465 “Then the Apostle divided the property, wives, and children of the Qurayza among the Muslims. Allah’s Messenger took his fifth of the booty.” Tabari VIII:38 “The Prophet selected for himself from among the Jewish women of the Qurayza, Rayhanah bt. Amr. She became his concubine. When he predeceased her, she was still in his possession. When the Messenger of Allah took her as a captive, she showed herself averse to Islam and insisted on Judaism.”

Tabari VIII:39 “Then the Messenger of Allah sent Sa’d bin Zayd with some of the Qurayza captives to Najd, and in exchange for them he purchased horses and arms.” Tabari VIII:40 “The Messenger of God commanded that furrows should be dug in the ground for the Qurayza. Then he sat down. Ali and Zubayr began cutting off their heads in his presence.”