Narrated `Aisha:Allah's Messenger (ﷺ) in his fatal illness said, "Allah cursed the Jews and the Christians, for they built the places of worship at the graves of their prophets." And if that had not been the case, then the Prophet's grave would have been made prominent before the people. So (the Prophet (ﷺ) ) was afraid, or the people were afraid that his grave might be taken as a place for worship

Narrated Abu Bakr bin `Aiyash:Sufyan at-Tammar told me that he had seen the grave of the Prophet (ﷺ) elevated and convex

Narrated `Urwa:When the wall fell on them (i.e. graves) during the caliphate of Al-Walid bin `Abdul Malik, the people started repairing it, and a foot appeared to them. The people got scared and thought that it was the foot of the Prophet. No one could be found who could tell them about it till I (`Urwa) said to them, "By Allah, this is not the foot of the Prophet (ﷺ) but it is the foot of `Umar