Musnad Ahmad 1153:641

Abu Sa’id, the freed slave of Banu Hashim, narrated to us, saying: Husayn ibn Nafi’ al-Mazini narrated to us—my father said: "This Husayn is sound in hadith"—he said: al-Hasan narrated to us, from Sa’d ibn Hisham, that he entered upon the Mother of the Believers, ‘Aishah, and asked her about the prayer of the Messenger of Allah (may Allah bless him and grant him peace). She said: "He used to pray eight rak’ahs at night, and he would perform witr with the ninth. And he would pray two rak’ahs while sitting." She mentioned the ablution, that he would stand for his prayer, and he would order his purification and his siwak. "When the Messenger of Allah (may Allah bless him and grant him peace) grew older, he prayed six rak’ahs and performed witr with the seventh, and he prayed two rak’ahs while sitting." She said: "He did not cease to be upon that until he was taken [in death]." I said: "I want to ask you about celibacy (tabattul), so what is your opinion on it?" She said: "Do not do it. Have you not heard Allah, the Almighty and Majestic, say: {And We have already sent messengers before you and assigned to them wives and descendants} [Ar-Ra’d: 38]? So do not practice celibacy." He said: So he left having gained understanding. He arrived in Basra, and he did not stay there but a short while until he went out to the land of Makran, where he was killed while upon the best of his deeds.