Musnad Ahmad 30:3650

'Abd al-Malik ibn 'Amr narrated to us, Hisham ibn Sa'd narrated to us, from al-Maqburi, from Abu Hurayrah, that the Prophet (peace and blessings of Allah be upon him) said: "Men must certainly cease their boasting about peoples who are nothing but coals from the coals of Hell, or they will surely be more insignificant to Allah than the dung beetle that rolls filth with its nose." And he said: "Indeed, Allah the Almighty has removed from you the arrogance of the pre-Islamic era (Jahiliyyah) and its boasting about forefathers. [People are either] a pious believer or a wretched sinner. Mankind are the children of Adam, and Adam was from dust."