Hadith 2000
أَخْبَرَنَا 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
Sahih (Abu Ghuddah)
Sunan an-Nasaʾi 2000 · Book 21, Hadith 183