I say, and with God's success: It is permissible to pray in a mosque that contains a grave without any dislike; due to the consensus that has occurred among the companions and those who followed them, the leaders of religion, without any objection. The grave of the Prophet, peace be upon him, is in the mosque by the consensus of the companions, as the mosque was expanded during the caliphate of Umar ibn Abdul Aziz in Medina to include the grave in the presence of the companions without any objection. Most of the mosques of Muslims throughout history have contained the graves of scholars and righteous individuals. And God knows best.