What is the ruling on praying in a mosque that contains a grave?

Praying at graves, taking them as mosques, and building mosques over them are innovations that contravene the guidance of the Prophet, peace and blessings be upon him. Many texts have been reported that prohibit and severely condemn this. The Prophet, peace and blessings be upon him, forbade taking graves as mosques and cursed those who did so, and he informed that among the worst of people are those who take graves as mosques. Imam Ibn al-Qayyim held the view that a mosque built over a grave should be demolished, and the deceased should be exhumed if buried in a mosque, for a mosque and a grave cannot coexist in Islam.