Sunan an-Nasa'i 475
سنن النسائي#475Sahihأَخْبَرَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا هُشَيْمٌ، قَالَ أَنْبَأَنَا مَنْصُورُ بْنُ زَاذَانَ، عَنِ الْوَلِيدِ بْنِ مُسْلِمٍ، عَنْ أَبِي الصِّدِّيقِ النَّاجِيِّ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، قَالَ كُنَّا نَحْزُرُ قِيَامَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي الظُّهْرِ وَالْعَصْرِ فَحَزَرْنَا قِيَامَهُ فِي الظُّهْرِ قَدْرَ ثَلاَثِينَ آيَةً قَدْرَ سُورَةِ السَّجْدَةِ فِي الرَّكْعَتَيْنِ الأُولَيَيْنِ وَفِي الأُخْرَيَيْنِ عَلَى النِّصْفِ مِنْ ذَلِكَ وَحَزَرْنَا قِيَامَهُ فِي الرَّكْعَتَيْنِ الأُولَيَيْنِ مِنَ الْعَصْرِ عَلَى قَدْرِ الأُخْرَيَيْنِ مِنَ الظُّهْرِ وَحَزَرْنَا قِيَامَهُ فِي الرَّكْعَتَيْنِ الأُخْرَيَيْنِ مِنَ الْعَصْرِ عَلَى النِّصْفِ مِنْ ذَلِكَ .
It was narrated that Abu Sa'eed Al-Khudri said:"We used to estimate how long the Messenger of Allah (ﷺ) stood when praying in Zuhr and 'Asr. We estimated that he stood in Zuhr for as long as it take to recite thirty verses, as long as Surat As-Sajadah in the fits two Rak'ahs, and half that in the last two. And we estimated that he stood for as long in the fits two Rak'ahs, and half that in the last two. And we estimated that he stood for as long in the first two Rak'ahs of 'Asr as he stood in the last two Rak'ahs of Zuhr, and we estimated that he stood half as long as that in the last two Rak'ahs of 'Asr
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: 5:28