It was narrated from Makhramah bin Sulaiman that Kuraib - the freed slave of Ibn 'Abbas - told him:

"I asked Ibn 'Abbas: 'How did the Messenger of Allah (ﷺ) pray at night?' He said: 'He prayed eleven Rak'ahs including Witr, then he slept deeply until I could hear him snoring, then Bilal came to him and said: "The prayer, O Messenger of Allah!" Then he got up and prayed two brief Rak'ahs then led the people in prayer, and he did not perform Wudu'.'"

أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ عَبْدِ الْحَكَمِ، عَنْ شُعَيْبٍ، عَنِ اللَّيْثِ، قَالَ حَدَّثَنَا خَالِدٌ، عَنِ ابْنِ أَبِي هِلاَلٍ، عَنْ مَخْرَمَةَ بْنِ سُلَيْمَانَ، أَنَّ كُرَيْبًا، مَوْلَى ابْنِ عَبَّاسٍ أَخْبَرَهُ قَالَ سَأَلْتُ ابْنَ عَبَّاسٍ قُلْتُ كَيْفَ كَانَتْ صَلاَةُ رَسُولِ اللَّهِ صلى الله عليه وسلم بِاللَّيْلِ فَوَصَفَ أَنَّهُ صَلَّى إِحْدَى عَشْرَةَ رَكْعَةً بِالْوِتْرِ ثُمَّ نَامَ حَتَّى اسْتَثْقَلَ فَرَأَيْتُهُ يَنْفُخُ وَأَتَاهُ بِلاَلٌ فَقَالَ الصَّلاَةُ يَا رَسُولَ اللَّهِ ‏.‏ فَقَامَ فَصَلَّى رَكْعَتَيْنِ وَصَلَّى بِالنَّاسِ وَلَمْ يَتَوَضَّأْ ‏.‏