Hadith Q119
إِذْ لَوْ كَانَ لِقَدْرِ الْمَاءِ الَّذِي يَتَوَضَّأُ بِهِ الْمَرْءُ مِقْدَارٌ لَا يَجُوزُ أَنْ يَزِيدَ عَلَيْهِ وَلَا يَنْقُصَ مِنْهُ شَيْئًا، لَمَا جَازَ أَنْ يَجْتَمِعَ اثَنَانِ وَلَا جَمَاعَةٌ عَلَى إِنَاءٍ وَاحِدٍ، فَيَتَوَضَّئُوا مِنْهُ جَمِيعًا، وَالْعِلْمُ مُحِيطٌ أَنَّهُمْ إِذَا اجْتَمَعُوا عَلَى إِنَاءٍ وَاحِدٍ يَتَوَضَّئُونَ مِنْهُ؛ فَإِنَّ بَعْضَهُمْ أَكْثَرُ حَمْلًا لِلْمَاءِ مِنْ بَعْضٍ
Because if a specific amount of water had been prescribed for ablution, such that using less or more than that amount would not be permissible, then it would also be impermissible for two people or a group to perform ablution together from one vessel. This is because it is certain that when they perform ablution together from one vessel, some people will use more water and some will use less.
Hadith 119
Lady Aisha (may Allah be pleased with her) narrates that I and the Messenger of Allah (peace and blessings be upon him) used to perform ablution from the same vessel.
Hadith 120
Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates that during the blessed time of the Messenger of Allah (peace be upon him), we men and women used to perform ablution together and would wash our hands from the same vessel.
Hadith 121
It is narrated from Sayyiduna Abdullah (may Allah be pleased with him) that he saw the Prophet (peace and blessings of Allah be upon him) and his noble companions (may Allah be pleased with them) performing ablution together with their women; men and women were all performing ablution from the same vessel.