"Is it permissible to perform the Greeting of the Mosque (Tahiyyat al-Masjid) in mosques that have residences above them? "

"Building a mosque underneath or above a house does not negate its status as a mosque, and it is permissible if the mosque and the dwelling are initially established in this manner. The Shafi'is, Malikis, and Hanbalis have permitted designating the upper part of a house as a mosque without its lower part, and vice versa. The mosque built under a house has all the rulings of mosques, so the greeting prayer of the mosque is performed in it like any other mosque.

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