Sunan an-Nasa'i 150
It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) went out to the graveyeard and said:
"Peace be upon you, abode of believing people. If Allah wills, we shall join you soon. Would that I had seen our brothers." They said: "O Messenger of Allah, are we not your brother?" He said: "You are my Companions. My brothers are those who have not come yet. And I will reach the Hawd before you." They said: "O Messenger of Allah, how will you know those of your Ummah who come after you?" He said: "Don't you think that if a man has a horse with a white blaze and white feet among horses that are solid black, he will recognize his horse?" They said: "Of course." He said: "They will come on the Day of Resurrection with glittering white faces and glittering white hands and feet because of Wudu', and I will reach the Hawd before them."
أَخْبَرَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنِ الْعَلاَءِ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم خَرَجَ إِلَى الْمَقْبُرَةِ فَقَالَ ‏"‏ السَّلاَمُ عَلَيْكُمْ دَارَ قَوْمٍ مُؤْمِنِينَ وَإِنَّا إِنْ شَاءَ اللَّهُ بِكُمْ لاَحِقُونَ وَدِدْتُ أَنِّي قَدْ رَأَيْتُ إِخْوَانَنَا ‏"‏ ‏.‏ قَالُوا يَا رَسُولَ اللَّهِ أَلَسْنَا إِخْوَانَكَ قَالَ ‏"‏ بَلْ أَنْتُمْ أَصْحَابِي وَإِخْوَانِي الَّذِينَ لَمْ يَأْتُوا بَعْدُ وَأَنَا فَرَطُهُمْ عَلَى الْحَوْضِ ‏"‏ ‏.‏ قَالُوا يَا رَسُولَ اللَّهِ كَيْفَ تَعْرِفُ مَنْ يَأْتِي بَعْدَكَ مِنْ أُمَّتِكَ قَالَ ‏"‏ أَرَأَيْتَ لَوْ كَانَ لِرَجُلٍ خَيْلٌ غُرٌّ مُحَجَّلَةٌ فِي خَيْلٍ بُهْمٍ دُهْمٍ أَلاَ يَعْرِفُ خَيْلَهُ ‏"‏ ‏.‏ قَالُوا بَلَى ‏.‏ قَالَ ‏"‏ فَإِنَّهُمْ يَأْتُونَ يَوْمَ الْقِيَامَةِ غُرًّا مُحَجَّلِينَ مِنَ الْوُضُوءِ وَأَنَا فَرَطُهُمْ عَلَى الْحَوْضِ ‏"‏ ‏.‏