Sunan an-Nasa'i 509
سنن النسائي#509Sahihأَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنْ أَبِي بَكْرِ بْنِ عُثْمَانَ بْنِ سَهْلِ بْنِ حُنَيْفٍ، قَالَ سَمِعْتُ أَبَا أُمَامَةَ بْنَ سَهْلٍ، يَقُولُ صَلَّيْنَا مَعَ عُمَرَ بْنِ عَبْدِ الْعَزِيزِ الظُّهْرَ ثُمَّ خَرَجْنَا حَتَّى دَخَلْنَا عَلَى أَنَسِ بْنِ مَالِكٍ فَوَجَدْنَاهُ يُصَلِّي الْعَصْرَ قُلْتُ يَا عَمِّ مَا هَذِهِ الصَّلاَةُ الَّتِي صَلَّيْتَ قَالَ الْعَصْرَ وَهَذِهِ صَلاَةُ رَسُولِ اللَّهِ صلى الله عليه وسلم الَّتِي كُنَّا نُصَلِّي .
It was narrated that Abu Bakr bin 'Uthman bin Sahl bin Hunaif said:"I heard Abu Umamah bin Sahl say: 'We prayed Zuhr with 'Umar bin 'Abdul-'Aziz, then we went out and entered upon Anas bin Malik, and we found him praying 'Asr.'" I said: "O uncle, what is this prayer that you prayed?" He said: "'Asr; this is the prayer of the Messenger of Allah (ﷺ) that we used to pray with him
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: 6:16