In one narration the wording is: Sayyiduna Imam al-Hasan (may Allah be pleased with him) said: "After the dream I have seen, I will not fight." After this the narrator mentioned the narration as before, and further on it contains these words: "I saw Sayyiduna Uthman (may Allah be pleased with him) with his hand placed on Sayyiduna Umar (may Allah be pleased with him), and after them I saw blood. I asked: 'What is this?' I was told: 'This is the blood of Sayyiduna Uthman (may Allah be pleased with him), concerning which he is petitioning Allah Almighty (to take account).'" Abu Ya'la recorded all of these narrations with two chains; one of the two chains contains narrators whom I do not know, and the other chain contains a narrator, Sufyan bin Waki', who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 14562