From `Abdul `Aziz Bin `Abdullah Ibn Baz to His Excellency the honorable brother: H. M. R. May Allah grant you all success!
Assalamu `alaykum warahmatullah wabarakatuh (May Allah's Peace, Mercy, and Blessings be upon you!)
I have received your noble letter dated in 17/10/1392 A.H. The concerned letter involved a question about the ruling on transferring the stones of a very old Masjid (mosque) that was destructed by floods. Is it permissible for a person to take the stones of such a Masjid to their house and keep them in their possession? It is worth mentioning that such a Masjid might have contained a grave.
My answer is: When a Masjid is ruined because of floods or any other reason, it is prescribed for the people of its area to reconstruct it and start performing Salah (Prayer) in it again. This is because the Prophet (peace be upon him) said: Whoever builds a Masjid for the sake of Allah, Allah will build a house for him in Jannah (Paradise). Moreover, `Aishah (may Allah be pleased with her) said: The Messenger of Allah (peace be upon him) commanded us to build Masjids (mosques) in different localities (i.e. in the locality of each tribe separately) and that they should be kept clean and be perfumed. (Related by Ahmad, Abu Dawud, and Ibn Majah with a good Sanad (chain ofnarrators)).