(17) باب صَلاَةِ اللَّيْلِ وَعَدَدِ رَكَعَاتِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي اللَّيْلِ وَأَنَّ الْوِتْرَ رَكْعَةٌ وَأَنَّ الرَّكْعَةَ صَلاَةٌ صَحِيحَةٌ
'A'isha reported:
Never did the earlier part of the dawn find the Messenger of Allah (ﷺ) but sleeping in my house or near me.
Reference: Sahih Muslim 742
In-book reference: Book 6, Hadith 160
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1615