Narrated Thawban:

An animal was brought to the Messenger of Allah ﷺ while he was going with a funeral. He refused to ride on it. When the funeral was away, the animal was brought to him and he rode on it. He was asked about it. He said: The angels were on their feet. I was not to ride while they were walking. When they went away, I rode.

حَدَّثَنَا يَحْيَى بْنُ مُوسَى الْبَلْخِيُّ، أَخْبَرَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ، عَنْ أَبِي سَلَمَةَ بْنِ عَبْدِ الرَّحْمَنِ بْنِ عَوْفٍ، عَنْ ثَوْبَانَ، أَنَّ رَسُولَ اللَّهِ ﷺ أُتِيَ بِدَابَّةٍ وَهُوَ مَعَ الْجَنَازَةِ فَأَبَى أَنْ يَرْكَبَهَا فَلَمَّا انْصَرَفَ أُتِيَ بِدَابَّةٍ فَرَكِبَ فَقِيلَ لَهُ فَقَالَ
" إِنَّ الْمَلاَئِكَةَ كَانَتْ تَمْشِي فَلَمْ أَكُنْ لأَرْكَبَ وَهُمْ يَمْشُونَ فَلَمَّا ذَهَبُوا رَكِبْتُ " .