مُوَطَّأُ مَالِكٍ
Muwatta Malik 106
Purity
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ عَبْدِ اللَّهِ بْنِ كَعْبٍ، مَوْلَى عُثْمَانَ بْنِ عَفَّانَ أَنَّ مَحْمُودَ بْنَ لَبِيدٍ الأَنْصَارِيَّ، سَأَلَ زَيْدَ بْنَ ثَابِتٍ عَنِ الرَّجُلِ، يُصِيبُ أَهْلَهُ ثُمَّ يُكْسِلُ وَلاَ يُنْزِلُ فَقَالَ زَيْدٌ يَغْتَسِلُ . فَقَالَ لَهُ مَحْمُودٌ إِنَّ أُبَىَّ بْنَ كَعْبٍ كَانَ لاَ يَرَى الْغُسْلَ . فَقَالَ لَهُ زَيْدُ بْنُ ثَابِتٍ إِنَّ أُبَىَّ بْنَ كَعْبٍ نَزَعَ عَنْ ذَلِكَ قَبْلَ أَنْ يَمُوتَ .
Yahya related to me from Malik from Yahya ibn Said from Abdullah ibn Kab, the mawla of Uthman ibn Affan that Mahmud ibn Labid al-Ansari asked Zayd ibn Thabit about a man who penetrated his wife but became listless and did not ejaculate. Zayd ibn Thabit said, "He does ghusl." Mahmud said to him, "Ubayy ibn Kab used not to think that ghusl was necessary," but Zayd ibn Thabit said, "Ubayy ibn Kab drew away from that before he died."
Arabic/English book reference: Book 2, Hadith 76