Musnad Ahmad 30:1189

Rawh narrated to us, Ibn Abi Dhi’b narrated to us, from Sa’id al-Maqburi, from Abu Hurairah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The Hour will not be established until my Ummah takes the ways of the nations and generations before it, span by span and cubit by cubit." They said: "O Messenger of Allah, like Persia and Rome?" He said: "And are the people [who matter] anything other than those?"