Sahih al-Bukhari 5859
Narrated Abu Juhaifa:
I came to the Prophet (ﷺ) 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 صلى الله عليه وسلم وَهْوَ فِي قُبَّةٍ حَمْرَاءَ مِنْ أَدَمٍ، وَرَأَيْتُ بِلاَلاً أَخَذَ وَضُوءَ النَّبِيِّ صلى الله عليه وسلم وَالنَّاسُ يَبْتَدِرُونَ الْوَضُوءَ، فَمَنْ أَصَابَ مِنْهُ شَيْئًا تَمَسَّحَ بِهِ، وَمَنْ لَمْ يُصِبْ مِنْهُ شَيْئًا أَخَذَ مِنْ بَلَلِ يَدِ صَاحِبِهِ‏.‏