What is the ruling on not completing the construction of a mosque that a husband intended to build on his wife's land after his death, given the presence of a nearby mosque, and is it permissible to estimate the value of the construction and allocate it to another charitable deed?

If a wife dedicates land for the construction of a mosque, its ownership transfers from her immediately upon endowment (waqf) and its ownership transfers to Allah Almighty. This land may not be used for anything other than that for which it was endowed, even if another mosque is built nearby. However, if it is merely an intention and the actual endowment has not taken place, the land remains the property of its owner, and nothing results from the mere intention.