The Book of Prayer
Bulugh al-Maram #458
كتاب الصلاة
وَعَنْهَا قَالَتْ: «كَانَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -يُصَلِّي مِنْ اَللَّيْلِ ثَلَاثَ عَشْرَةَ رَكْعَةً, يُوتِرُ مِنْ ذَلِكَ بِخَمْسٍ, لَا يَجْلِسُ فِي شَيْءٍ إِلَّا فِي آخِرِهَا.»
Narrated:
Allah's Messenger (ﷺ) used to pray thirteen Rak'at during the night, offering a Witr out of that with five and sitting only during the last of them.
وَعَنْهَا قَالَتْ: "كَانَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -يُصَلِّي مِنْ اَللَّيْلِ ثَلَاثَ عَشْرَةَ رَكْعَةً, يُوتِرُ مِنْ ذَلِكَ بِخَمْسٍ, لَا يَجْلِسُ فِي شَيْءٍ إِلَّا فِي آخِرِهَا."
Allah's Messenger (ﷺ) used to pray thirteen Rak'at during the night, offering a Witr out of that with five and sitting only during the last of them.
— Bulugh al-Maram, Hadith 458