Musnad Abu Ya'la al-Mawsili 105:16

Sulayman al-Shadhkuni narrated to us, Isma'il ibn Aban narrated to us, 'Ali ibn al-Hazwar narrated to us, he said: I heard Abu Maryam say: I heard 'Ammar ibn Yasir say: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "The righteous have not adorned themselves in the world with anything like asceticism in the world."