Book 004, Number 1079:At least one modern Islamic scholar says that such a mosque, if built after the grave was already in place, must be destroyed. It appears to be the mainstream thinking in Wahhabism.
'A'isha reported: The Messenger of Allah (may peace be upon him) said during his illness from which he never recovered: Allah cursed the Jews and the Christians that they took the graves of their prophets as mosques. She ('A'isha) reported: Had it not been so, his (Prophet's) grave would have been in an open place, but it could not be due to the fear that it may not be taken as a mosque.
Book 004, Number 1080:
Abu Huraira reported: The Messenger of Allah (may peace be upon him) said: Let Allah destroy the Jews for they have taken the graves of their apostles as places of worship.
Book 004, Number 1081:
Abu Huraira reported: The Messenger of Allah (may peace be upon him) said: Let there be curse of Allah upon the Jews and the Christians for they have taken the graves of their apostles as places of worship.
Book 004, Number 1082:
'A'isha and Abdullah reported: As the Messenger of Allah (may peace be upon him) was about to breathe his last, he drew his sheet upon his face and when he felt uneasy, he uncovered his face and said in that very state: Let there be curse upon the Jews and the Christians that they have taken the graves of their apostles as places of worship. He in fact warned (his men) against what they (the Jews and the Christians) did.
So how come no Muslims are publicly calling to destroy the mosques that are at the Tomb of the Patriarchs, Rachel's Tomb, the Tomb of Joseph and Samuel's' Tomb, among others?
Could it be because the Jews have built places of worship there, and it is more important to erase Jewish connections to the land than it is to observe a series of explicit hadiths?