What is the ruling on not fulfilling a vow due to illness?

Question:
He says: A woman vowed that if her son were healed from his illness, she would fast two months every year. Her son has been healed, and she has fasted for approximately four years. In recent years, she was afflicted with an illness, which is a migraine, and this illness makes fasting difficult for her, as when she fasts and abstains from eating, the migraine attacks her.

Answer:
As is known, if a person vows to obey Allah, he is required to do so, based on the saying of the Prophet (peace and blessings be upon him) However, if he is unable to fulfill the vow, if he is incapable of fulfilling the vow, he is excused; he is excused. And as long as he is able to fulfill the vow, it is obligatory for him to do so, based on the saying of His Lord: "They fulfill their vows" and "Let them fulfill their vows." The Prophet (peace and blessings be upon him) says: So as long as he is able, it is obligatory for him to fulfill the vow, and if he is unable, he is excused.