"I came to Al-Madinah, and I was performing Hajj, and while we were in our camping place unloading our mounts, someone came to us and said: 'The people have gathered in the Masjid.' I looked and found the people gathered, and in the midst of them was a group; there I saw 'Ali bin Abi Talib, Az-Zubair, Talhah and Sa'd bin Abi Waqqas, may Allah have mercy on them. When I got there, it was said that 'Uthman bin 'Affan had come. He came, wearing a yellowish cloak. I said to my companion: Stay where you are until I find out what is happening. 'Uthman said: Is 'Ali here? Is Az-Zubair here? Is Talhah here? Is Sa'd here? They said: Yes. He said: I adjure you by Allah, beside Whom there is none worthy of worship, are you aware that the Messenger of Allah said: Whoever buys the Mirbad of Banu so and so, Allah will forgive him, and I bought it, then I came to the Messenger of Allah and told him, and he said: Add it to our Masjid and the reward for it will be yours? They said: Yes. He said: I adjure you by Allah, beside Whom there is none worthy of worship, are you aware that the Messenger of Allah said: Whoever buys the well of Rumah, Allah will forgive him, so I came to the Messenger of Allah and said: I have bought the well of Rumah. He said: Give it to provide water for the Muslims, and the reward for it will be yours? They said: Yes. He said: 'I adjure you by Allah, beside Whom there is none worthy of worship, are you aware that the Messenger of Allah said: Whoever equips the army of Al-'Usrah (i.e. Tabuk), Allah will forgive him, so I equipped them until they were not lacking even a rope or a bridle?' They said: Yes. He said: O Allah, bear witness, O Allah, bear witness, O Allah, bear witness."
Sunan an-Nasa'i Book 29, Hadith 13