(1)
Abu Sa'id (RAA) narrated that the Messenger of Allah (ﷺ) said:
"Stand up when you see a funeral procession, and he who accompanies it should not sit down until the coffin is placed on the ground." Agreed upon.
Reference: Bulugh al-Maram 572
In-book reference: Book 3, Hadith 41
English translation: Book 3, Hadith 597