Ruling on praying in a mosque built under a residential building

Question:
Is it permissible to pray in a mosque built under a residential building?

Answer:
If there is a pressing need for a mosque that is part of a building, there is nothing wrong with it. If the people of a certain location have no mosque and a person donates the ground floor for them to use as a mosque, there is no blame on them. However, if the mosque already exists, a building should not be constructed on top of it. If the mosque is established, its space should be left for the needs of the mosque. But if the mosque is new to the building, and the building was there first, and the owner donates the ground floor, the second floor, or the third floor for the mosque, there is nothing wrong with it, and may Allah reward him with good, if they have a need for it.