Sahih Bukhari | Volume 5 | Hadith Number 725
Narrated by Urwa bin Az-Zubair
'Aisha said, "The Prophet said during his fatal illness, "Allah cursed the Jews for they took the graves of their prophets as places for worship." 'Aisha added, "Had it not been for that (statement of the Prophet) his grave would have been made conspicuous. But he was afraid that it might be taken as a place for worship."