Musannaf Ibn Abi Shaybah 40683 — reports on Siffin

Muhammad bin Umarah bin Khuzaymah bin Thabit said: My grandfather (may Allah be pleased with him) kept away from weapons in the Battle of Siffin and the Battle of the Camel. But when Sayyiduna Ammar (may Allah be pleased with him) was martyred, he drew his sword from its sheath and said: "I heard the Messenger of Allah (peace and blessings be upon him) say: 'Ammar will be killed by a rebellious party.'" Then he fought and was martyred.