Musnad Ahmad Hadith 17778

Muhammad bin Amr (may Allah be pleased with him) says that when Ammar bin Yasir (may Allah be pleased with him) was martyred, Amr bin Hazm (may Allah be pleased with him) went to Amr bin Aas (may Allah be pleased with him) and informed him that Ammar (may Allah be pleased with him) had been martyred, and that the Prophet (peace and blessings of Allah be upon him) had said that Ammar would be killed by a rebellious group? Upon hearing this, Amr bin Aas (may Allah be pleased with him) recited "Inna lillah" in distress, stood up anxiously, and went to Muawiyah (may Allah be pleased with him). Muawiyah (may Allah be pleased with him) asked him, "What has happened to you?" He replied that Ammar (may Allah be pleased with him) had been martyred. Muawiyah (may Allah be pleased with him) said, "Ammar (may Allah be pleased with him) has indeed been martyred, but what is the reason for your condition?" He said, "I heard the Prophet (peace and blessings of Allah be upon him) say that Ammar would be killed by a rebellious group." Muawiyah (may Allah be pleased with him) said, "You would have fallen in your own urine! Did we kill him? He was killed by Ali (may Allah be pleased with him) and his companions; they brought him and threw him among our spears."