The Messenger of Allah ﷺ used to pray thirteen units during the night, making five of them his witr prayer, and he would not sit during them except at the very last one.
كان رسول الله ﷺ يصلي من الليل ثلاث عشرة ركعة، يوتر من ذلك بخمس، لا يجلس في شيء إلا في آخرها.
Muslim reported it in "Prayer of the Traveler" (737) through the route of Hisham bin Urwa, from his father, from Ayesha, and she mentioned something similar.