Narrated `Abdullah bin `Abbas:
That once he stayed overnight (in the house) of his aunt Maimuna. the wife of the Prophet. He added: I lay on the cushion transversely and Allah's Messenger (ﷺ) lay along with his wife in the lengthwise direction of the pillow. Allah's Messenger (ﷺ) slept till the middle of the night, either a bit before or a bit after it, and then woke up rubbing the traces of sleep off his face with his hands and then he recited the last ten Verses of Surat-al-`Imran, got up and went to a hanging water skin. He then performed the ablution from it, and it was perfect ablution, and then stood up to offer the prayer. I too did the same as he had done, and then went to stand beside him. Allah's Messenger (ﷺ) put his right hand on my head and held and twisted my right ear. He then offered two rak`at, then two rak`at, then two rak`at, then two rak`at, then two rak`at. then two rak`at, and finally one rak`a, the witr. Then he lay down again till the Muadhdhin (i.e. the call-maker) came to him, whereupon he got up and offered a light two-rak`at prayer, and went out (to the Mosque) and offered the (compulsory congregational) Fajr prayer.
USC-MSA web (English) reference: Vol. 6, Book 60, Hadith 95
Arabic reference: Book 65, Hadith 4571