Hadith: The Prophet (may Allah's peace and blessings be upon him) called for water, and he was brought a wide shallow vessel with some water in it. He put his fingers in it

عن أنس بن مالك رضي الله عنه قال: حَضَرَتِ الصلاةُ فقامَ مَنْ كان قريبَ الدارِ إلى أَهْلِهِ، وبَقِيَ قَوْمٌ، فأُتِيَ رسولُ اللهِ صلى الله عليه وسلم بِمِخْضَبٍ مِنْ حِجَارَةٍ، فَصَغُرَ المِخْضَبُ أَنْ يَبْسُطَ فيهِ كَفَّهُ، فتَوَضَّأَ القومُ كلهم. قالوا: كم كنتم؟ قال: ثمانينَ وزيادةً. وفي رواية: أَنَّ النبيَّ صلى الله عليه وسلم دعا بإناءٍ من مَاءٍ، فأُتِيَ بقَدَحٍ رَحْرَاحٍ فيهِ شَيْءٌ من ماءٍ، فوضعَ أَصَابِعَهُ فيهِ، قال أنس: فَجَعَلْتُ أَنْظُرُ إلى الماءِ يَنْبُعُ مِنْ بَيْنِ أَصَابِعِهِ، فَحَزَرْتُ مَنْ تَوَضَّأَ ما بَيْنَ السبعينَ إلى الثمانينَ.
[صحيح] - [متفق عليه، بروايات متعددة]

Anas ibn Mālik (may Allah be pleased with him) reported: It was time for prayer. Those who were close to their homes went to their families (to perform ablution). Some people remained. The Messenger of Allah (may Allah's peace and blessings be upon him) was brought a stone pot. It was too small for him to open his palm therein. All of the people made ablution.” They said: “How many of you were there?” He said: "Eighty and more.” Another narration reads: "The Prophet (may Allah's peace and blessings be upon him) called for water, and he was brought a wide shallow vessel with some water in it. He put his fingers in it. Anas said: "I saw water flowing from between his fingers. I then counted those who performed ablution and found them between seventy and eighty."
[Authentic hadith] - [Al-Bukhari and Muslim with multiple versions]

Explanation

Anas (may Allah be pleased with him) tells that the ‘Asr (Afternoon) prayer became due while the Companions were with the Prophet (may Allah's peace and blessings be upon him) in Madīnah. Those whose homes were nearby went there to make ablution. Those with distant homes stayed. The Prophet (may Allah's peace and blessings be upon him) was brought a stone pot with some water in it. The pot, however, was so small to accommodate the Prophet's hand. Nevertheless, the Companions, who were eighty or more, were able to make ablution therefrom.