What is the ruling on praying in a mosque built on cemetery land after the graves were exhumed, with the possibility of unremoved remains still existing?

Muslims must respect the graves of their deceased and it is not permissible to exhume them unless there is a necessity. If the graves of disbelievers are exhumed, or if the graves of Muslims are encroached upon and then exhumed, it is permissible to build a mosque in their place. However, if any part of the graves remains, it is not permissible to build a mosque over them.

If a mosque is built over Muslim graves, prayer in it is not permissible and it must be demolished because the graves predate it. However, if the graves are in a corner of the mosque and a separating wall is built between the mosque and those graves, then this is permissible and prayer is valid.

If there is a grave within a mosque, it must be exhumed and the bones transferred to the town's cemetery. If the mosque was built after the grave existed, then the mosque must be demolished and removed, because the Messenger of Allah (peace and blessings of Allah be upon him) warned against building mosques over graves.