Is it permissible to use an unused storeroom as a communal prayer room (musalla) for the neighborhood despite the objection of some building residents, and would that be considered a sin?

The five daily prayers must be performed in congregation at the mosque if the call to prayer (adhan) is heard, based on the Prophet's (peace be upon him) saying: "Whoever hears the call [to prayer] and does not come, there is no prayer for him except for an excuse." This is further supported by the hadith of the blind man whom the Prophet (peace be upon him) commanded to answer the call to prayer.

If the mosque is far away, it is prescribed to build a mosque or designate a place for prayer, such as the aforementioned warehouse, provided its owner grants permission. This is one of the outward symbols of Islam. The Prophet (peace be upon him) commanded the building of mosques in residential areas (districts) to facilitate congregational prayer for the people of that area. This is a communal obligation (fard kifayah), and there should ideally be a mosque in every neighborhood.

The consent of neighbors is not a condition; rather, they should be reassured and informed that external loudspeakers will not be used except for the adhan. They should also be shown the beneficial impact of the mosque in bringing them together, fostering harmony, and encouraging children to pray.