Musnad Abu Ya'la al-Mawsili 108:143

A man from the Ansar came to the Messenger of Allah, may Allah bless him and grant him peace, and said: "O Messenger of Allah, I have a slave girl, and I practice *azl* (coitus interruptus) with her." The Prophet, may Allah bless him and grant him peace, said: "Whatever is decreed for her will come to her." Then he came to him after that and said: "O Messenger of Allah, the slave girl has become pregnant." The Messenger of Allah, may Allah bless him and grant him peace, said: "Whatever soul Allah has decreed to come forth, it will surely come to be."