Narrated Abu Juhaifa:

I came to the Prophet while he was inside a red leather tent, and I saw Bilal taking the remaining water of the ablution of the Prophet, and the people were taking of that water and rubbing it on their faces;
and whoever could not get anything of it, would share the moisture of the hand of his companion (and then rub it on his face).

حَدَّثَنَا مُحَمَّدُ بْنُ عَرْعَرَةَ، قَالَ حَدَّثَنِي عُمَرُ بْنُ أَبِي زَائِدَةَ، عَنْ عَوْنِ بْنِ أَبِي جُحَيْفَةَ، عَنْ أَبِيهِ، قَالَ أَتَيْتُ النَّبِيَّ ﷺ وَهْوَ فِي قُبَّةٍ حَمْرَاءَ مِنْ أَدَمٍ، وَرَأَيْتُ بِلاَلاً أَخَذَ وَضُوءَ النَّبِيِّ ﷺ وَالنَّاسُ يَبْتَدِرُونَ الْوَضُوءَ، فَمَنْ أَصَابَ مِنْهُ شَيْئًا تَمَسَّحَ بِهِ، وَمَنْ لَمْ يُصِبْ مِنْهُ شَيْئًا أَخَذَ مِنْ بَلَلِ يَدِ صَاحِبِهِ.