Hadith
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّهُ كَانَ لاَ يَعْزِلُ وَكَانَ يَكْرَهُ الْعَزْلَ .
Yahya related to me from Malik from Nafi that Abdullah ibn Umar did not practise coitus interruptus and thought that it was disapproved
Sahih · Salim al-Hilali
Muwatta Malik 1260 ·Book 29, Hadith 57·Also available on sunnah.com·