Sahih al-Bukhari 1140
Sahih al-Bukhari · Book 19: Prayer at Night (Tahajjud) · How was the Salat of the Prophet (pbuh) and how many Rak'a he used to offer at night?
Narrated `Aisha:
حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُوسَى ، قَالَ أَخْبَرَنَا حَنْظَلَةُ ، عَنِ الْقَاسِمِ بْنِ مُحَمَّدٍ ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتْ كَانَ النَّبِيُّ صلى الله عليه وسلم يُصَلِّي مِنَ اللَّيْلِ ثَلاَثَ عَشْرَةَ رَكْعَةً مِنْهَا الْوِتْرُ وَرَكْعَتَا الْفَجْرِ.
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.