Sunan an-Nasa'i 1681
سنن النسائي#1681Sahihأَخْبَرَنَا إِسْحَاقُ بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ، عَنْ سُفْيَانَ، عَنْ أَبِي حَصِينٍ، عَنْ يَحْيَى بْنِ وَثَّابٍ، عَنْ مَسْرُوقٍ، عَنْ عَائِشَةَ، قَالَتْ أَوْتَرَ رَسُولُ اللَّهِ صلى الله عليه وسلم مِنْ أَوَّلِهِ وَآخِرِهِ وَأَوْسَطِهِ وَانْتَهَى وَتْرُهُ إِلَى السَّحَرِ .
It was narrated that Aishah said:"The Messenger of Allah (ﷺ) prayed witr at the beginning (of the night) and at the end, and in the middle. And toward the end of his life, he settled on performing witr at the end of the night
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 20:84