The prayer of the Prophet (ﷺ) used to be of thirteen rak`at, i.e. of the night prayer.
Sahih al-Bukhari Book 19, Hadith 19
← Previous Hadith A man said, "O Allah's Messenger (ﷺ)! How is the prayer of the night?" He said, "Two rak`at followed by two rak`at and so on, and when you apprehend the approaching dawn, offer one rak`a as witr."

Sahih al-Bukhari Book 19, Hadith 18 Next Hadith → I asked Aisha about the night prayer of Allah's Messenger (ﷺ) and she said, "It was seven, nine or eleven rak`at besides the two rak`at of the Fajr prayer (i.e. Sunna). "

Sahih al-Bukhari Book 19, Hadith 20