The Book of Prayer - Travellers
حَدَّثَنَا ابْنُ نُمَيْرٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا حَنْظَلَةُ، عَنِ الْقَاسِمِ بْنِ مُحَمَّدٍ، قَالَ سَمِعْتُ عَائِشَةَ، تَقُولُ كَانَتْ صَلاَةُ رَسُولِ اللَّهِ صلى الله عليه وسلم مِنَ اللَّيْلِ عَشَرَ رَكَعَاتٍ وَيُوتِرُ بِسَجْدَةٍ وَيَرْكَعُ رَكْعَتَىِ الْفَجْرِ فَتِلْكَ ثَلاَثَ عَشْرَةَ رَكْعَةً .It is reported on the authority of 'A'isha that the prayer of Allah's Messenger (ﷺ) in the night consisted of ten rak'ahs. He observed a Witr and two rak'ahs (of Sunan) of the dawn prayer, and thus the total comes to thirteen rak'ahs
From Sahih Muslim, whose reports the scholars accept as authentic.