Musnad Abu Ya'la al-Mawsili 152:248

Abu Khaythama narrated to us, Uthman ibn Umar narrated to us, Za'ida narrated to us, from Asim ibn Abi al-Najud, from Shaqiq, from Abdullah, that the Messenger of Allah (may Allah bless him and grant him peace) said: "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."