Yahya bin Sa'id (may Allah have mercy on him) says: My paternal uncle narrated to me: When we were drawn up for the Battle of the Camel, Sayyiduna Ali (may Allah be pleased with him) said: Let no one shoot an arrow, thrust with a spear or strike with a sword; you are not to start the fighting, and you are to speak to them gently. And I think he also said: Whoever succeeds today will succeed on the Day of Resurrection too. We remained like that until the day was well advanced, when they all called out together: O vengeance for the blood of Uthman (may Allah be pleased with him)! Sayyiduna Ali (may Allah be pleased with him) called Muhammad ibn al-Hanafiyyah (may Allah have mercy on him), who was in front of us and was carrying the banner, and asked: O Ibn al-Hanafiyyah, what are they calling out? He replied: They are calling for vengeance for the blood of Uthman (may Allah be pleased with him), O Commander of the Believers. Sayyiduna Ali (may Allah be pleased with him) raised his hands and said: O Allah, today throw the killers of Uthman down on their faces.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16743