Is it permissible to build a zawiya or a mosque in another location to fulfill a vow to build a mosque on land owned by the questioner and her husband, especially given the close proximity of neighboring mosques to their land?

The vow to build a mosque or a zawiya (religious lodge) in its designated location must be fulfilled as long as there is hope of worshippers, based on the Prophet, peace and blessings be upon him, who said: "Whoever vows to obey Allah, let him obey Him," and "Indeed, among the good deeds and merits that will reach a believer after his death... is a mosque he built." If there is no need for another mosque in the specified location, a specialized real estate authority should be consulted to assess the place. Then, you and your husband should disburse its value to purchase another location in an area that needs a mosque and build it there.