Disposing of money donated to a specific entity
Is it permissible to spend the money remaining from donations made towards
building a mosque on constructing an adjoining hospital instead of a minaret for the mosque? Please note that the minaret has not yet been built and the land designated for the hospital was originally demarcated for establishing a mosque.
Whenever possible, money donated to a particular beneficiary such as a mosque, hospital or school must be spent on the entity stipulated by the donors. Any remaining money or money in surplus of the needs of the beneficiary must be given to a similar entity to achieve the aim of the donors. Since the collector, whether an individual or legal entity, is considered an agent of the donors, it is impermissible to deviate from the object of the commissioner. But if the contribution was not designated for a specific body and was meant for diverse charitable acts or an undesignated ongoing charity, it is then permissible to use the surplus money for a new charity project.
Based on the above, if the money was collected for the benefit of the established mosque or by reason of it being a mosque, then it is necessary to spend the surplus money to build a minaret for it, expand it or to build another mosque. However, it would be impermissible to use it to build a hospital with the money. On the other hand, if the money was collected for unspecified charitable acts, it is permissible to use the surplus to build a hospital.
Allah the Almighty knows best.