What is the ruling on someone who vowed to donate twenty-five thousand riyals for the sake of Allah, but does not possess this amount and has no income except for a small allowance from her husband?

A contingent vow is Islamically disliked (makruh), but it must be fulfilled if it is a vow of obedience, according to the Prophet, peace and blessings be upon him, who said: "Whoever vows to obey Allah, let him obey Him." If the wish is fulfilled, the promised amount must be spent on good deeds. This obligation is not waived except in case of inability. In the event of inability to fulfill it, an expiation for a broken oath (kaffarat yamin) is required, as the Prophet, peace and blessings be upon him, said: "Whoever makes a vow he cannot fulfill, its expiation is the expiation of an oath."