Is it permissible to dispose of an area designated for prayer inside a residential building by selling it or using it for purposes other than that for which it was prepared, knowing that it has not been used for prayer for more than 15 years? If that is not permissible, then is it permissible to sell it and donate its price to a general charitable project?

The area designated for prayer is considered an endowment (waqf), and an endowment is the dedication of an asset and the channeling of its usufruct (benefits) seeking divine reward. It is among the acts of piety whose reward does not cease after death. It is not permissible to dispose of it by sale or otherwise as long as its use is possible. However, if the endowment cannot be utilized for the purpose for which it was endowed, it is permissible to transfer it to another location, or to sell it and use its price for a purpose that serves the original objective of the endowment. Therefore, if the area can be utilized as a prayer space, do not dispose of it otherwise. If it cannot, then there is no objection to selling it for the highest possible price and allocating its proceeds to a similar purpose.