What is the ruling regarding someone who vowed to fast every Friday for life for the recovery of his mother, and she has indeed recovered? Does this conflict with the disfavor of singling out Friday for fasting? What if it coincides with an Eid day? What are the implications if he becomes unable to fast due to illness or old age? Is there a way to be released from this vow?

The Hanafis and Malikis are of the view that it is permissible to fast on Friday alone, and obligatory to fast on it for whoever vowed to do so. As for the Shafi'is and Hanbalis, they dislike singling out Friday for fasting, and this is the most preponderant opinion, due to the Prophet's prohibition of it, unless it coincides with a customary fast or is joined by a day before or after it.

In the case of vowing to fast on Friday, the Shafi'is hold that it is obligatory to fulfill the vow, albeit with dislike, while the Hanbalis hold that it is commendable to offer an expiation for an oath (kaffarat yamin) and not fast on it, but if one does fast on it, it suffices. The preponderant opinion is that it is obligatory to fulfill it, except in case of inability, in which case an expiation for an oath suffices. If Friday coincides with a day on which fasting is prohibited, such as the two Eid days, then breaking the fast and making it up later becomes obligatory.