'A'isha reported that the Messenger of Allah ﷺ used to pray eleven rak'ahs at night, observing the Witr with a single rak'ah, and when he had finished them, he lay down on his right side, till the Mu'adhdhin came to him and he (the Holy Prophet) then observed two short rak'ahs (of Sunan of the dawn prayer). (Using translation from Muslim 736a)
أَنَّ رَسُولَ اللهِ ﷺ كَانَ يُصَلِّي بِاللَّيْلِ إِحْدَى عَشْرَةَ رَكْعَةً يُوتِرُ مِنْهَا بِوَاحِدَةٍ فَإِذَا فَرَغَ مِنْهَا اضْطَجَعَ عَلَى شِقِّهِ الْأَيْمَنِ حَتَّى يَأْتِيَهُ الْمُؤَذِّنُ فَيُصَلِّيَ رَكْعَتَيْنِ خَفِيفَتَيْنِ