What is the ruling on praying in a mosque that has a grave inside its enclosure?

Question:
Honorable Shaykh, may Allah grant you success. He says: A person prayed in a mosque that has a grave in it; he says the grave is inside the mosque's enclosure. Is his prayer valid?

Answer:
No, it is not permissible to pray at graves or toward them. The Messenger (peace and blessings be upon him) forbade that, so this is not permissible. A mosque built over a grave is not to be prayed in; because it is not a mosque for Allah, but rather a shrine for exalting this dead person or seeking blessing from him. This is not permissible. And do not take the graves as mosques, for I forbid you from that, except that those before you used to take the graves as mosques, so do not take the graves as mosques, for I forbid you from that. This was in his final moments (peace and blessings be upon him), at the end of his life, when he advised this. Yes. And we say: What about mosques that contradict this and have graves built for them? Yes.