Sahih Bukhari Volume 4, Book 61, Hadith 3576

حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ مُبَارَكٍ، حَدَّثَنَا حَزْمٌ، قَالَ سَمِعْتُ الْحَسَنَ، قَالَ حَدَّثَنَا أَنَسُ بْنُ مَالِكٍ ـ رضى الله عنه ـ قَالَ خَرَجَ النَّبِيُّ صلى الله عليه وسلم فِي بَعْضِ مَخَارِجِهِ وَمَعَهُ نَاسٌ مِنْ أَصْحَابِهِ، فَانْطَلَقُوا يَسِيرُونَ، فَحَضَرَتِ الصَّلاَةُ فَلَمْ يَجِدُوا مَاءً يَتَوَضَّئُونَ، فَانْطَلَقَ رَجُلٌ مِنَ الْقَوْمِ، فَجَاءَ بِقَدَحٍ مِنْ مَاءٍ يَسِيرٍ فَأَخَذَهُ النَّبِيُّ صلى الله عليه وسلم فَتَوَضَّأَ، ثُمَّ مَدَّ أَصَابِعَهُ الأَرْبَعَ عَلَى الْقَدَحِ ثُمَّ قَالَ ‏"‏ قُومُوا فَتَوَضَّئُوا ‏"‏‏.‏ فَتَوَضَّأَ، الْقَوْمُ حَتَّى بَلَغُوا فِيمَا يُرِيدُونَ مِنَ الْوَضُوءِ، وَكَانُوا سَبْعِينَ أَوْ نَحْوَهُ‏

Narrated By Anas bin Malik : The Prophet went out on one of his journeys with some of his companions. They went on walking till the time of the prayer became due. They could not find water to perform the ablution. One of them went away and brought a little amount of water in a pot. The Prophet took it and performed the ablution, and then stretched his four fingers on to the pot and said (to the people), "Get up to perform the ablution." They started performing the ablution till all of them did it, and they were seventy or so persons.