Sunan an-Nasa'i 2000
سنن النسائي#2000Sahihأَخْبَرَنَا إِسْمَاعِيلُ بْنُ مَسْعُودٍ، قَالَ حَدَّثَنَا خَالِدٌ، قَالَ حَدَّثَنَا شُعْبَةُ، قَالَ أَخْبَرَنِي مُحَمَّدُ بْنُ الْمُنْكَدِرِ، عَنْ مَسْعُودِ بْنِ الْحَكَمِ، عَنْ عَلِيٍّ، قَالَ : رَأَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم قَامَ فَقُمْنَا، وَرَأَيْنَاهُ قَعَدَ فَقَعَدْنَا .
It was narrated from 'Ali bin Abi Talib that:mention was made of standing at the funeral until the body is placed in the grave. 'Ali bin Abi Talib said: "The Messenger of Allah stood, then he sat down
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: 21:183