Musannaf Ibn Abi Shayba 27:385

Abdullah ibn Idris narrated to us, from Husayn, from Umar ibn Jawwan, from al-Ahnaf ibn Qays, who said: We arrived in Medina, and Uthman came, and it was said, "This is Uthman." He entered, and he had a yellow mantle with which he had covered his head. He said, "Is Ali here?" They said, "Yes." He said, "Is Talha here?" They said, "Yes." He said, "Is al-Zubayr here?" They said, "Yes." He said, "Is Sa’d here?" They said, "Yes." He said, "I adjure you by Allah, besides whom there is no god, do you know that the Messenger of Allah (may Allah bless him and grant him peace) said, 'Whoever purchases the drying-yard of the sons of so-and-so, Allah will forgive him'? So I purchased it for twenty thousand or twenty-five thousand, then I came to the Prophet (may Allah bless him and grant him peace) and said, 'I have purchased it.' He said, 'Place it into our mosque, and its reward is for you.'" They said, "O Allah, yes." He said, "I adjure you by Allah, besides whom there is no god, do you know that the Messenger of Allah (may Allah bless him and grant him peace) said, 'Whoever purchases the well of Rummah, Allah will forgive him'? So I purchased it for such-and-such, then I came to him and said, 'I have purchased it.' He said, 'Make it a watering place for the Muslims, and its reward is for you.'" They said, "O Allah, yes." He said, "I adjure you by Allah, besides whom there is no god, do you know that the Messenger of Allah (may Allah bless him and grant him peace) looked at the faces of the people and said, 'Whoever equips these, Allah will forgive him'—meaning the Army of Hardship—so I equipped them until they lacked neither a hobble nor a nose-rein?" They said, "O Allah, yes." He said, "O Allah, bear witness," three times.