Sunan an Nasai
The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day
Hadith #120
20.120
أَخْبَرَنَا إِسْحَاقُ بْنُ مَنْصُورٍ، قَالَ أَنْبَأَنَا عَبْدُ الرَّحْمَنِ، عَنْ سُفْيَانَ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ يُوتِرُ بِخَمْسٍ وَلاَ يَجْلِسُ إِلاَّ فِي آخِرِهِنَّ .
Hisham bin Urwah narrated from his father, from Aishah, that:The Prophet (ﷺ) used to pray witr with five and he did not sit except in the last (rak'ah) of them