Musnad Ahmad 31:611

Muhammad ibn Isma'il narrated to us, al-Dahhak narrated to us, from Muhammad ibn Yahya ibn Habban, from Ibn Muhayriz al-Shami, that he heard Abu Sirmah al-Mazini and Abu Sa'id al-Khudri saying: We obtained captives in the expedition of Banu al-Mustaliq, and it is the expedition in which the Messenger of Allah, peace and blessings of Allah be upon him, obtained Juwayriyah. Among us were those who wanted to take wives, and among us were those who wanted to enjoy [them] and sell [them]. So we consulted one another regarding *al-'azl* (coitus interruptus). We mentioned that to the Prophet, peace and blessings of Allah be upon him, and he said: "It does not matter if you do not practice *al-'azl*, for Allah has ordained whatever He is creating until the Day of Resurrection."