(48) باب مَنْ تَبِعَ جَنَازَةً فَلاَ يَقْعُدُ حَتَّى تُوضَعَ عَنْ مَنَاكِبِ الرِّجَالِ، فَإِنْ قَعَدَ أُمِرَ بِالْقِيَامِ
Narrated Abu Sa`id Al-Khudri:
The Prophet (ﷺ) said, "When you see a funeral procession, you should stand up, and whoever accompanies it should not sit till the coffin is put down."
Reference: Sahih al-Bukhari 1310
In-book reference: Book 23, Hadith 69
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 23, Hadith 397