Musnad Abu Ya'la al-Mawsili 130:45

Ishaq ibn Abi Isra'il narrated to us, Hammad narrated to us, from Thabit and 'Abd al-'Aziz, from Anas: That the Prophet (peace be upon him) prayed the morning prayer when he arrived from Khaybar in the darkness before dawn. Then he mounted and said: "Allahu Akbar (God is the Greatest), Khaybar is ruined. Indeed, when we descend into the courtyard of a people, evil is the morning of those who have been warned." He said: So they came out running in the streets, and they were saying: "Muhammad and the Khamis." Hammad said: Meaning the army. The Messenger of Allah (peace be upon him) prevailed, so he killed their fighters and took their offspring captive. He said: Safiyyah belonged to Dihyah al-Kalbi, then she later became the property of the Messenger of Allah (peace be upon him), so he married her and made her dowry her emancipation. 'Abd al-'Aziz said to Thabit: "O Abu Muhammad, did you ask Anas what he gave her as a dowry?" He said to him: "He told me he gave her herself as a dowry." Then Thabit smiled.