Ahnaf reported, "We set out as pilgrims and passed through Medina. While we were at our lodging, someone came to us and said, 'The people are alarmed and have gathered in the mosque.' So my companion and I went out, and there were the people gathered around a small group in the mosque."He continued, "I made my way through them until I stood over them, and there were Ali bin Abu Talib, Zubayr, Talha, and Saad bin Abu Waqqas. It was not long before Uthman came walking up.He asked, 'Is Ali here?'They said, 'Yes.'He asked, 'Is Zubayr here?'They said, 'Yes.'He asked, 'Is Talha here?'They said, 'Yes.'He asked, 'Is Saad here?'They said, 'Yes.'He said, 'I adjure you by Allah, beside whom there is no god, do you know that the Messenger of Allah ﷺ said, "Whoever buys the enclosure of such-and-such a clan, Allah will forgive him," so I bought it, then I came to the Messenger of Allah ﷺ and said, "I have bought it," and he said, "Make it part of our mosque, and its reward is yours"?'They said, 'Yes.'He said, 'I adjure you by Allah, beside whom there is no god, do you know that the Messenger of Allah ﷺ said, "Who will buy the well of Rumah?" so I bought it for such-and-such, then I came to the Messenger of Allah ﷺ and said, "I have bought it," meaning the well of Rumah, and he said, "Make it a source of water for the Muslims, and its reward is yours"?'They said, 'Yes.'He said, 'I adjure you by Allah, beside whom there is no god, do you know that the Messenger of Allah ﷺ looked at the faces of the people on the day of the army of hardship and said, "Whoever equips these men, Allah will forgive him," so I equipped them until they lacked neither halter nor rope?'They said, 'By Allah, yes.'He said, 'O Allah, bear witness. O Allah, bear witness. O Allah, bear witness.' Then he departed."
حدثنا بهز حدثنا أبو عوانة حدثنا حصين
قال الأحنف انطلقنا حجاجا فمررنا بالمدينة فبينما نحن في منزلنا إذ جاءنا آت فقال الناس من فزع في المسجد فانطلقت أنا وصاحبي فإذا الناس مجتمعون على نفر في المسجد قال فتخللتهم حتى قمت عليهم فإذا علي بن أبي طالب والزبير وطلحة وسعد بن أبي وقاص قال فلم يكن ذلك بأسرع من أن جاء عثمان يمشي فقال أهاهنا علي قالوا نعم قال أهاهنا الزبير قالوا نعم قال أهاهنا طلحة قالوا نعم قال أهاهنا سعد قالوا نعم قال أنشدكم بالله الذي لا إله إلا هو أتعلمون أن رسول الله ﷺ قال من يبتاع مربد بني فلان غفر الله له فابتعته فأتيت رسول الله ﷺ فقلت إني قد ابتعته فقال اجعله في مسجدنا وأجره لك قالوا نعم قال أنشدكم بالله الذي لا إله إلا هو أتعلمون أن رسول الله ﷺ قال من يبتاع بئر رومة فابتعتها بكذا وكذا فأتيت رسول الله ﷺ فقلت إني قد ابتعتها يعني بئر رومة فقال اجعلها سقاية للمسلمين وأجرها لك قالوا نعم قال أنشدكم بالله الذي لا إله إلا هو أتعلمون أن رسول الله ﷺ نظر في وجوه القوم يوم جيش العسرة فقال من يجهز هؤلاء غفر الله له فجهزتهم حتى ما يفقدون خطاما ولا عقالا قالوا اللهم نعم قال اللهم اشهد اللهم اشهد اللهم اشهد ثم انصرف
Its isnad is sahih. Amr bin Jawan Tamimi Saadi is mentioned by Ibn Hibban in Thiqat. The hadith was narrated by Nasai, at length and in abridged form, 2:65-66, 123-124, and Ibn Kathir mentioned it in Tarikh 7:177, quoting from the Musnad. See also 420.