1747. The fast of the day of ‘Ðd al-aÃÎÁ and ‘Ðd al-fiÔr are forbidden. Similarly, if a person does not know whether it is the last day of ShaÞbÁn or the first day of the month of Ramadan, but fasts with the intention of the first day of the month of Ramadan, it will be forbidden.
1748. If a woman violates the right of her husband by observing a recommended fast, then she must not fast. In fact, even if his rights are not infringed upon, the recommended precaution is that she should not fast without his permission.
1749. It is forbidden for children to fast if it hurts their parents.
1750. If a son or daughter observes a recommended fast without seeking his father’s permission, and the father prohibits him from it during the day, he will have to break his fast if disobeying his father would hurt him. The same will apply if the mother prohibits him and disobeying her would hurt her.
1751. A person who knows that fasting is not harmful for him must fast, even if a doctor says that it is harmful for him. On the contrary, if a person is certain or has a reasonable dout that it will cause a significant harm to him, or fears the harm—given that it is a fear that has basis amongst intelligent people—then he must not fast, even if a doctor says that it is not harmful for him. If he does fast, it will not be in order, unless the fast turns out not to be harmful for him and he had made the intention of attaining proximity to Allah. In this case, the fast will be valid.
1752. If a person considers it possible that fasting would entail a significant harm for him, and through that possibility, he develops a fear (for the harm), he must not fast if the possibility that he entertains is considered reasonable by intelligent people. Should he fast, it will not be valid, unless it turns out not to be harmful for him, and he had made the intention of attaining proximity.
1753. If a person believes that fasting will not cause him any significant harm, and having fasted, he realizes after maghrib that it did in fact entail significant harm for him, he will have to observe its qaÃÁ.
1754. Other than the aforementioned forbidden fasts, there are other fasts which are forbidden as well, and have been mentioned in more detailed texts.
1755. The fast of the day of ‘ÀshÙrÁ is not permissible based on obligatory precaution. As for fasting on the day that a person doubts whether it is the day of ‘Arafah or the day of ‘Ðd al-aÃÎÁ, it is makrÙh to do so.