What is the ruling on someone who vowed to fast the White Days every month for the rest of their life for their father's recovery, but they cannot bear fasting and find extreme difficulty in it? Should they feed ten poor people for each month, or can they expiate their vow with another form of expiation?

A conditional vow is disliked (makruh), but it must be fulfilled if the condition upon which it was made is met, as the Prophet, peace and blessings be upon him, said: "Whoever vows to obey Allah, let him obey Him."

Normal hardship does not waive the obligation to fulfill it, and it is not permissible to change a vow. Whoever vows to fast perpetually is obligated to do so.

The hardship that permits breaking the fast is that which exceeds the ordinary. If the one who made the vow breaks their fast due to an excuse that is expected to cease, they are obligated to make up the fast without expiation (kaffarah).

It is not permissible to abandon fasting and resort to expiation or feeding others except in cases of permanent inability that is not expected to cease, such as a chronically ill person or a very old person. In such cases, an expiation for an oath (kaffarat yamin) is sufficient.