Is it permissible to abandon the building of a mosque that was vowed to be built on land inherited by minor children, in the event of insufficient funds for that purpose and the need of some heirs for their share, and is it permissible for the mother who vowed a large part of her share for the mosque to retract her vow?

Building mosques is among the desirable acts of obedience, the reward of which continues for a person after their death. A Muslim must fulfill their vow if they have vowed an act of obedience. If the mother vowed to build a mosque with the value of her deceased husband's land, her vow is only valid concerning her own share of the land. If her share is sufficient to build the mosque, she is obligated to fulfill it. Otherwise, she should use it towards the costs of another mosque. A vow is not valid for what the person making the vow does not own, and it is not permissible to revoke this vow or benefit from the vowed amount designated for building the mosque.