Musnad Ahmad 31:513

Yahya narrated to us, he said: Ibn Abi Arubah narrated to us, from Qatadah, from al-Hasan, from Abu Sa’id, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said regarding *al-‘azl* (coitus interruptus): "You do not create it, and you do not provide for it. Let it remain in its place, for that is only the decree."