(10) باب كَيْفَ كَانَ صَلاَةُ النَّبِيِّ صلى الله عليه وسلم وَكَمْ كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يُصَلِّي مِنَ اللَّيْلِ
Narrated `Aisha:
The Prophet (p.b.u.h) used to offer thirteen rak`at of the night prayer and that included the witr and two rak`at (Sunna) of the Fajr prayer.
Reference: Sahih al-Bukhari 1140
In-book reference: Book 19, Hadith 21
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 21, Hadith 241