Musnad Abu Ya'la al-Mawsili 218:6

Abu Hisham Muhammad ibn Yazid ibn Rifa'ah narrated to us, Yunus ibn Bukayr narrated to us, from Ibrahim ibn Isma'il ibn Mujammi', he said: Uthman ibn Ka'b narrated to me, from a man who is called Rabi', from Safiyyah bint Huyayy, she said: The Messenger of Allah (may Allah bless him and grant him peace) let me ride behind him on the rear of his she-camel at night. She said: I began to doze off, so the Messenger of Allah (may Allah bless him and grant him peace) would touch me with his hand and say: "O you, O daughter of Huyayy." And he began to say: "O Safiyyah, I apologize to you for what I did to your people; they said such-and-such to me, they said such-and-such to me."