"When any one of you sees a funeral and is not walking with it, let him stand up until it has passed him, or until (the body) is placed (in the grave) before if passes him." (Using translation from Nasāʾī 1915)   

عَنِ النَّبِيِّ ﷺ قَالَ إِذَا رَأَى أَحَدُكُمُالْجَنَازَةَ وَلَمْ يَكُنْ مَاشِيًا مَعَهَا فَلْيَقُمْ حَتَّى تُجَاوِزَهُ أَوْ تُوضَعَ  

[Machine] The Prophet ﷺ said, "Whoever prays upon a deceased and does not walk with the funeral procession, let him stand until it departs from him. And whoever walks with it, let him not sit until it is laid down."  

قَالَ رَسُولُ اللهِ ﷺ مَنْ صَلَّى عَلَى جَنَازَةٍ فَلَمْ يَمْشِ مَعَهَا فَلْيَقُمْ حَتَّى تَغِيبَ عَنْهُ وَمَنْ مَشَى مَعَهَا فَلَا يَجْلِسْ حَتَّى تُوضَعَ