Sunan an-Nasa'i 1916
سنن النسائي#1916SahihIt was narrated form 'Amir bin Rabi'ah Al-'Adawi that the Messenger of Allah said:"When you see a funeral, stand up until it has passed you, or (the body) is placed (in the grave)
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 - Agreed Upon
In-book reference: 21:99