Musnad Ahmad 30:717

Mu'awiyah ibn 'Amr narrated to us, Abu Ishaq al-Fazari said: Al-Awza'i said, from al-Zuhri, from Ibn al-Musayyib, from Abu Hurayrah, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "May those who took the graves of their prophets as places of worship be cursed."