كتاب الصلاة
2  
The Book of Prayer
Bulugh al-Maram 380
Narrated ['Aishah (RA)]:
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. [Agreed upon].
وَعَنْهَا قَالَتْ: { مِنْ كُلِّ اَللَّيْلِ قَدْ أَوْتَرَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-فَانْتَهَى وِتْرُهُ إِلَى اَلسَّحَرِ } مُتَّفَقٌ عَلَيْهِمَا .‏ 1‏ .‏
Reference : Bulugh al-Maram 380
In-book reference : Book 2, Hadith 380
English translation : Book 2, Hadith 375
Hadith Text
Reference