Mosques that contain graves are not to be prayed in

Q: The brother M. A. N. from Bait Turayf, Dakahlia, Egypt, says in his question: Is the prayer valid in mosques where there are graves?

A: It is not permissible to pray in mosques that contain graves, and it is obligatory to dig up the graves and transfer the remains to the public cemeteries, with each grave in its own pit like the rest of the graves. It is not permissible for any graves to remain there, whether the grave of a wali (close friend of Allah) or anyone else; because the Messenger (peace and blessings be upon him) forbade and warned against that, and he cursed the Jews and the Christians for their doing of it. It is established from him (peace and blessings be upon him) that he said: Aisha (may Allah be pleased with her) said: “He was warning against what they did.” It is agreed upon by al-Bukhari and Muslim. And he (peace and blessings be upon him) said, when Umm Salama and Umm Habiba informed him of a church in Abyssinia that contained images: It is agreed upon that it is authentic. And he (peace and blessings be upon him) said: Muslim narrated it in his Sahih from Jundub ibn Abdullah al-Bajali. So he (peace and blessings be upon him) forbade taking graves as mosques, and he cursed whoever did that, and he informed that they are the worst of creation. So it is obligatory to be cautious of that.
And it is known that whoever prays at a grave has taken it as a mosque, and whoever builds a mosque over it has taken it as a mosque. So it is obligatory that graves be kept away from mosques, and that no graves be placed in them, in obedience to the command of the Messenger (peace and blessings be upon him) and out of fear of the curse that came from our Lord (Glorified and Exalted is He) for whoever builds mosques over graves; because if one prays in a mosque that contains graves, Satan may make it attractive to him to call upon the dead, or seek aid from them, or pray to them, or prostrate to them, and thus major shirk (associating partners with Allah) occurs. And because this is the practice of the Jews and the Christians, it is obligatory that we differ from them and distance ourselves from their path and their evil deeds.
But if the graves are the old ones, and then the mosque was built over them, it is obligatory to demolish it and remove it; because it is the newly added element, as the scholars have explicitly stated, in order to cut off the causes of shirk (associating partners with Allah) and block the means to it. And success is from Allah.