Musnad Ahmad 30:2902

'Abd al-Rahman narrated to us, Hammad narrated to us, from Muhammad ibn Ziyad, who said: I heard Abu Hurayrah saying: I heard Abu al-Qasim (may Allah bless him and grant him peace) saying: "The fire of the children of Adam, which they kindle, is one part out of seventy parts of the fire of Hell." A man said: "It would have been sufficient." He said: "It has been made to exceed it by sixty-nine parts, each part being of equal heat."