Imam al-Shafi'i (may Allah have mercy on him) said: "The two sons of Sa'yah al-Qurazi accepted Islam while the Messenger of Allah (peace and blessings be upon him) was besieging Banu Qurayzah, and their Islam secured their lives and their property, that is, their date-palm orchards, land and other things."
Nafi' narrates from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Jews of Banu al-Nadir and Banu Qurayzah waged war against the Prophet (peace and blessings be upon him). So the Prophet (peace and blessings be upon him) exiled Banu al-Nadir, while he let Banu Qurayzah stay and showed them favour, but later Banu Qurayzah fought against him (peace and blessings be upon him). He (peace and blessings be upon him) killed their men and divided their women, property and children among the Muslims, except for those who joined the Messenger of Allah (peace and blessings be upon him); he gave them protection, and they accepted Islam.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18262