Amat Allah bint Razinah narrates from her mother that on the day of (Banu) Qurayzah and al-Nadir, he (the Prophet (peace and blessings be upon him)) brought Safiyyah (may Allah be pleased with her), leading her as a captive, until Allah granted him victory, with her arm in his hand. When she saw the captives, she said: I bear witness that there is no god but Allah and that you are the Messenger of Allah. So he (peace and blessings be upon him) let go of her arm and set her free, then proposed to her and married her, and gave her Razinah as her dower.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13745