It is narrated from Sayyiduna Hudhayfah bin al-Yaman (may Allah be pleased with him) that he heard the Messenger of Allah (peace and blessings be upon him) saying: "Ammar is such-and-such, such-and-such and such-and-such (possessed of the finest qualities), as long as he has not reached old age."
Imam al-Tabarani (may Allah have mercy on him) said: "This hadith is not narrated from Sayyiduna Hudhayfah (may Allah be pleased with him) except with this chain; Sa'd bin Aws al-Katib (may Allah have mercy on him) is alone in narrating it."