Sunan an-Nasa'i 1998
سنن النسائي#1998Sahihأَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنْ هِشَامٍ، وَالأَوْزَاعِيِّ، عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي سَعِيدٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا رَأَيْتُمُ الْجَنَازَةَ فَقُومُوا وَمَنْ تَبِعَهَا فَلاَ يَقْعُدَنَّ حَتَّى تُوضَعَ " .
It was narrated that Abu Sa'eed said:"The Messenger of Allah said: 'If you see a funeral, then stand up, and whoever follows it, then let him not sit down until (the body) is placed in the grave
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: 21:181