"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.'"
Jami` at-Tirmidhi Book 49, Hadith 96