Jami` at-Tirmidhi Book 49, Hadith 96
"I witnessed the Prophet (ﷺ) while he was exhorting support for the 'army of distress.' 'Uthman bin 'Affan stood and said: 'O Messenger of Allah! I will take the responsibility of one-hundred camels, including their saddles and water-skins, in the path of Allah.' Then he I will take the responsibility of three-hundred camels, including their saddles and water-skins, in the path of Allah.' So I saw the Messenger of Allah (ﷺ) descend from the Minbar while he was saying: 'It does not matter what 'Uthman does after this, it does not matter what 'Uthman does after this.'"
"When 'Uthman was besieged, he looked out over them from atop his house and said: 'I remind you by Allah. Do you know that when (mount) Hira shook, the Messenger of Allah (ﷺ) said: "Be firm O Hira! For there is none upon you except a Prophet, a Siddiq, and a martyr?"' They said: 'Yes.' He said: 'I remind you by Allah! Do you know that the Messenger of Allah (ﷺ) said, about the army of distress (Al-'Usrah): "Who will spend something which shall be accepted (by Allah)?" And the people were struggling during difficult times, so I prepared that army?' They said: 'Yes.' Then he said: 'I remind you by Allah. Do you know that no one drank from the well of Rumah but have to pay for it, then I bought it and made it for the rich, the poor, and the wayfarer?' They said: 'O Allah! Yes!'" And he listed other things. This Hadith is Hasan Sahih Gharib from this route; as a narration of Abu 'Abdur-Rahman As-Sulami from 'Uthman.
that 'Uthman went to the Prophet (ﷺ) with one-thousand Dinar" - Al-Hasan bin Waqi (one of the narrators) said: "And in another place in my book: 'In his garment when the 'army of distress' was being prepared. So he poured them into his lap.'" - 'Abdur-Rahman said: "So I saw the Prophet (ﷺ) turning them over in his lap, saying: 'Whatever 'Uthman does after today will not harm him,' two times."