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."
Muwatta Malik Book 2, Hadith 75