Sunan an-Nasa'i 1646
سنن النسائي#1646Sahihأَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا حَمَّادٌ، عَنْ بُدَيْلٍ، وَأَيُّوبَ، عَنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ، عَنْ عَائِشَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُصَلِّي لَيْلاً طَوِيلاً فَإِذَا صَلَّى قَائِمًا رَكَعَ قَائِمًا وَإِذَا صَلَّى قَاعِدًا رَكَعَ قَاعِدًا .
It was narrated that 'Aishah said:"The Messenger of Allah (ﷺ) used to pray for a long time at night. If he started to pray standing, he would bow standing and if he started to pray sitting, he would bow sitting
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: 20:49