Musannaf Ibn Abi Shayba 37:203

Muhammad ibn Ubaydah narrated to us, from al-A’mash, from Ibrahim al-Taymi, who said: Al-Harith ibn Suwayd was among a group of people, and he said: "Beware of the tribulations (fitan), for they have indeed appeared." A man said: "But you went out (to fight) with Ali." He replied: "And where would you find an Imam like Ali?"