Sunan an-Nasa'i 503
سنن النسائي#503Sahihأَخْبَرَنَا أَبُو عَبْدِ الرَّحْمَنِ عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ الأَذْرَمِيُّ، قَالَ حَدَّثَنَا عَبِيدَةُ بْنُ حُمَيْدٍ، عَنْ أَبِي مَالِكٍ الأَشْجَعِيِّ، سَعْدِ بْنِ طَارِقٍ عَنْ كَثِيرِ بْنِ مُدْرِكٍ، عَنِ الأَسْوَدِ بْنِ يَزِيدَ، عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ، قَالَ كَانَ قَدْرُ صَلاَةِ رَسُولِ اللَّهِ صلى الله عليه وسلم الظُّهْرَ فِي الصَّيْفِ ثَلاَثَةَ أَقْدَامٍ إِلَى خَمْسَةِ أَقْدَامٍ وَفِي الشِّتَاءِ خَمْسَةَ أَقْدَامٍ إِلَى سَبْعَةِ أَقْدَامٍ .
It was narrated that 'Abdullah bin Mas'ud said:"The Prophet (ﷺ) prayed Zuhr when the length of (a person's shadow) was between three and five feet in summer, and between five and seven feet in winter
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: 6:10