Musnad Ahmad 1153:715

Abu Salamah narrated to us, from Malik ibn Anas, from Sa’id al-Maqburi, from Abu Salamah ibn ‘Abd al-Rahman, who said: I asked ‘Aishah, and I said: How did the Messenger of Allah, may Allah bless him and grant him peace, pray during Ramadan? She said: His prayer in Ramadan and other than Ramadan was the same. He would pray eleven rak’ahs; four rak’ahs, so do not ask about their beauty and their length, then he would pray four rak’ahs, so do not ask about their beauty and their length, then he would pray three rak’ahs. I said: O Messenger of Allah, do you sleep before you perform the Witr? He said: "My eyes sleep, but my heart does not sleep."