Musannaf Ibn Abi Shayba 27:611

Abu Mu'awiyah narrated to us, he said: Al-A'mash narrated to us, from 'Amr ibn Murrah, from Abu al-Bakhtari, from 'Ali, he said: They said to him, "Tell us about the companions of the Messenger of Allah, may Allah bless him and grant him peace." They said, "Tell us about 'Ammar." He said: "A believer who is righteous, and if you mention him, he is mentioned."