Sunan an-Nasa'i 1999
سنن النسائي#1999SahihIt 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
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 21:182