I heard Ibn 'Abbas saying that the Messenger of Allah (ﷺ) observed thirteen rak'ahs at night.
Sahih Muslim Book 6, Hadith 231
← Previous Hadith I spent a night in the house of my mother's sister Maimuna, and the rest of the hadith is the same as narrated above.

Sahih Muslim Book 6, Hadith 230 Next Hadith → I would definitely watch at night the prayer observed by the Messenger of Allah (ﷺ). He prayed two short rak'ahs, then two long, long, long rak'ahs, then he prayed two rak'ahs which were shorter than the two preceding rak'ahs, then he prayed two rak'ahs which were shorter than the two preceding, then he prayed two rak'ahs which were shorter than the two preceding, then observed a single one (Witr), making a total of thirteen rak'ahs

Sahih Muslim Book 6, Hadith 232