Musnad Abu Ya'la al-Mawsili 109:77

Muhammad ibn Qudamah narrated to us, Ibn 'Uyaynah narrated to us, Sa'id ibn Hassan narrated to us, from 'Urwah ibn 'Iyad, from Jabir, who said: A man came to the Prophet, peace and blessings of Allah be upon him, and said: "I have a slave woman, and I practice *'azl* (coitus interruptus) with her." He said: "As for that, it does not prevent a matter that Allah has willed." He did not tarry long before he came and said to the Prophet, peace and blessings of Allah be upon him: "She has become pregnant." The Prophet, peace and blessings of Allah be upon him, said: "I am the servant of Allah and His Messenger."