I saw on the right side of Messenger of Allah ﷺ and on his left side two persons with white clothes on the Day of Uhtid fighting a desperate fight, and I saw them neither before nor after that. (Using translation from Muslim 2306b)
عَنْ يَمِينِ رَسُولِ اللهِ ﷺ وَعَنْ يَسَارِهِ يَوْمَ أُحُدٍ رَجُلَيْنِ عَلَيْهِمَا ثِيَابٌ بِيضٌ يُقَاتِلانِ عَنْهُ كَأَشَدِّ الْقِتَالِ مَا رَأَيْتُهُمَا قَبْلُ وَلا بَعْدُ