Musnad Ahmad 4:24

Bishr ibn Shu'ayb ibn Abi Hamzah narrated to us, my father narrated to me, from al-Zuhri, 'Urwah ibn al-Zubayr narrated to me, that 'Ubayd Allah ibn 'Adi ibn al-Khiyar informed him: That 'Uthman said to him: "Indeed, Allah sent Muhammad, upon him be peace and blessings, with the truth. I was among those who responded to Allah and His Messenger, and I believed in that which Muhammad, upon him be peace and blessings, was sent with. Then I performed the two migrations, and I attained the kinship of the Messenger of Allah, may Allah bless him and grant him peace, and I pledged allegiance to the Messenger of Allah, may Allah bless him and grant him peace. By Allah, I did not disobey him, nor did I deceive him, until Allah, the Almighty and Majestic, took his soul."