* It is haram to fast on the day of Eid-ul-Fitr and Eid-ul-Azha. It is also
haram to fast with the Niyyat of first fast of Ramadan on a day about which he
is not sure whether it is the last day of Sha'ban or the first of Ramadan.
* It is haram for a wife to keep a Mustahab fast if by so doing she would not be
able to attend to her duties to her husband. And the obligatory precaution is
that even if she can attend to her duties towards her husband, she should not
observe a Mustahab fast without his permission.
* It is haram for the children to observe a Mustahab fast if it causes emotional
suffering to their parents.
* If a son observes a Mustahab fast without the permission of his father, and
his father prohibits him from it during the day time, the son should break the
fast if his disobedience would hurt the feeling of his father.
* If a person knows that fasting is not harmful to him, he should fast even if
his doctor advises that it is harmful. And if a person is certain or has a
feeling that fasting is harmful to him, he should not fast even if the doctor
advises for it, and if he fasts in these circumstances, his fast will not be
valid if it turns out that the fast was actually harmful, or if it was not kept
with the Niiyyat of Qurbat.
* If a person has a strong feeling that it is harmful for him to fast, and owing
to that feeling, fear is created in his mind, and if that feeling is commonly
acceptable, he should not observe fast, and if he does, it will not be valid in
the way described in the foregoing rule.
* If a person who believes that fasting is not harmful to him, observes fast and
realizes after Maghrib that it was considerably harmful to him, he should, on
the basis of obligatory precaution, give the qadha of that day.
* Besides the fasts mentioned herein, there are other haram fasts also, the
details of which are found in relevant books.
* It is Makrooh to fast on 'Ashura (10th of Muharram). It is also Makrooh to
fast on the day about which one is not sure whether it is the day of 'Arafa or