Musnad Ahmad 26:593

'Abd al-Rahman narrated to us, Zaidah narrated to us, from 'Asim, from Shaqiq, from 'Abdullah, who said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Indeed, among the most evil of people are those whom the Hour overtakes while they are alive, and those who take graves as places of worship."