She was asked about the night prayer of the Messenger of Allah ﷺ, and she replied, "He used to pray thirteen units. Nine of them he prayed standing, including the witr, and two he prayed sitting. When he wanted to bow, he would stand up, then bow and prostrate. He would do that after the witr. Then when he heard the call for the dawn prayer, he would stand and pray two brief units."
أخبرنا عبيد الله بن فضالة بن إبراهيم قال حدثنا محمد يعني ابن المبارك الصوري قال حدثنا معاوية يعني ابن سلام عن يحيى بن أبي كثير قال أخبرني أبو سلمة بن عبد الرحمن أنه
عن صلاة رسول الله ﷺ من الليل فقالت كان يصلي ثلاث عشرة ركعة تسع ركعات قائما يوتر فيها وركعتين جالسا فإذا أراد أن يركع قام فركع وسجد ويفعل ذلك بعد الوتر فإذا سمع نداء الصبح قام فركع ركعتين خفيفتين
Muslim narrated it in the Book of the Travelers' Prayer, chapter on the night prayer and the number of units the Prophet ﷺ prayed at night, etc., hadith no. 126/738, from the hadith of Muawiya bin Salam through this same chain. It is also in Sunan Kabir, hadith no. 1449.Bukhari narrated it, hadith no. 619, from the hadith of Yahya bin Abu Kathir through this same chain, in very abbreviated form.