The Book of Funerals
21/47. Chapter:
Concession Allowing One To Not Stand Up
Sunan an-Nasai
أَخْبَرَنَا إِسْحَاقُ، قَالَ أَنْبَأَنَا النَّضْرُ، قَالَ حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، أَنَّ جَنَازَةً، مَرَّتْ بِرَسُولِ اللَّهِ صلى الله عليه وسلم فَقَامَ فَقِيلَ إِنَّهَا جَنَازَةُ يَهُودِيٍّ . فَقَالَ " إِنَّمَا قُمْنَا لِلْمَلاَئِكَةِ " .
It was narrated from Anas that: a funeral passed by the Messenger of Allah and he stood up. It was said: "It is the funeral of a Jew." He said: "We stood up for the angels."
Reference : Sunan an-Nasa'i 1929In-book reference : Book 21, Hadith 112English translation : Vol. 3, Book 21, Hadith 1931