But she faced circumstances in life, such as herding sheep, farming, and harvesting, and the like, which prevented her from fasting these days.

The questioner : My mother fell seriously ill and vowed that if Allah healed her from this illness, she would fast nine days every month. By Allah's permission, she was healed from her illness and fasted these days for several months, nine days each month. However, she faced circumstances in life, such as herding sheep, farming, and harvesting, and the like, which prevented her from fasting these days. So she limited herself to fasting three days each month, and she has not stopped fasting these three days to this day. What is required of her regarding leaving the remaining six days of the vow? And what must she do if she wants to be released from this vow?

The Shaykh : Praise be to Allah, Lord of the worlds, and I send prayers and peace upon our Prophet Muhammad, and upon his family and all his Companions. As for what follows, before answering the man's question about his mother's vow, I would like to say: A vow is disliked, and indeed, some scholars have forbidden it. This is because the Prophet (peace and blessings be upon him) prohibited it and said: Healing is not brought about by a vow, nor is wealth, nor is a child, nor is success in life or in studies, nor any other desirable matter or the removal of disliked matters. A vow does not bring these about, due to the generality of the saying of the Prophet (peace and blessings be upon him): The good is in the hand of Allah (Mighty and Majestic), and the Lord (Mighty and Majestic) is generous; He bestows upon His servants without them conditioning Him with anything they worship Him with, such as fasting, charity, or otherwise.
Furthermore, a vow is binding oneself to what Allah (Mighty and Majestic) has not obligated, and imposing upon oneself what He has not imposed. Moreover, many of those who make vows find it difficult to fulfill them afterward, and it becomes hard for them, and they may become negligent and abandon them. This is a great danger. Listen to the saying of Allah (Mighty and Majestic): What was their state after that? What happened? Allah the Exalted said: How many are the vow-makers who, when they vow something for the occurrence of a matter, and that matter occurs for which they tied the vow, how many of them wander right and left to find a scholar who grants them a dispensation to be released from what they have bound themselves to. So if you, O believer, know the outcome of a vow and know that the Prophet (peace and blessings be upon him) prohibited it, then you should avoid it in obedience to the Messenger (peace and blessings be upon him) and to protect yourself from binding yourself to what Allah has not bound you to.
But after all this, if a person vows an act of obedience, whether it is an absolute vow or one conditional upon a condition, it is obligatory for him to fulfill that act of obedience, because it becomes obligatory. This is based on the saying of the Prophet (peace and blessings be upon him): Your mother here made a vow that she is capable of fulfilling, which is to fast nine days every month if Allah the Exalted heals her. And Allah has healed her from the illness for which she tied this vow to healing. She is able to fast these nine days distributed over the month: three in the first ten days, three in the middle ten days, and three in the last ten days of the month, as long as she has not stipulated consecutiveness or indicated it. She has no release from this, except if she is unable to do so due to an inability that would permit her to break her fast in Ramadan, such as illness or the like. In that case, she may leave it for the sake of this excuse and make it up at another time.