The Book of Prayer
Bulugh al-Maram #459
كتاب الصلاة
وَعَنْهَا قَالَتْ: «مِنْ كُلِّ اَللَّيْلِ قَدْ أَوْتَرَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -فَانْتَهَى وِتْرُهُ إِلَى اَلسَّحَرِ» مُتَّفَقٌ عَلَيْهِمَا.
Narrated:
Allah's Messenger (ﷺ) offered Witr prayer (on different nights) at various hours, extending (from the 'Isha' prayer) up to the last hour of the night.
وَعَنْهَا قَالَتْ: "مِنْ كُلِّ اَللَّيْلِ قَدْ أَوْتَرَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -فَانْتَهَى وِتْرُهُ إِلَى اَلسَّحَرِ" مُتَّفَقٌ عَلَيْهِمَا .
Allah's Messenger (ﷺ) offered Witr prayer (on different nights) at various hours, extending (from the 'Isha' prayer) up to the last hour of the night.
— Bulugh al-Maram, Hadith 459