It is narrated from Sayyiduna Sirmah al-Udhri (may Allah be pleased with him), who said: The Messenger of Allah (peace and blessings be upon him) went on an expedition against Banu al-Mustaliq, and we obtained (among the captives) the finest women of the Arabs. We desired intimacy, as celibacy had become hard upon us, so we wanted to have intimacy with them and practise withdrawal ('azl). Then some of us said to others: It is not appropriate for us to do this while the Messenger of Allah (peace and blessings be upon him) is among us; we should ask him. So we asked him (peace and blessings be upon him), and the Messenger of Allah (peace and blessings be upon him) said: "Practise withdrawal or do not; every soul that Allah has decreed to come into existence until the Day of Resurrection will certainly come into existence."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7377