Night -supererogatory- prayers of the Messenger of Allah (PBUH) were ten rak'ahs, then he prays the witr with an odd/single rak'ah, then two -supererogatory- rak'ahs before Al-Fajr prayer. So those were thirteen rak'ahs.

The Prophet (PBUH) prayed until his feet became swollen, so people said: Why would you burden yourself with this, when Allah has already forgiven you for your former and latter sins? He said: Should I not be a grateful servant?

Abu Salamah asked 'A'ishah, how was the prayer of the Messenger of Allah (PBUH) in Ramadan? She said: The Messenger of Allah did not exceed eleven rak’ahs in Ramadan or at any other time. He prays four rak'ahs, do not ask how thorough and prolonged they were. Then he prays four, do not ask how thorough and prolonged they were. Then he prays three. Then 'A'ishah said: So I said: O Messenger of Allah, Do you sleep before you pray the Witr prayer? He said: O 'A'ishah, my eyes sleep but my heart does not.