Vowing to fast for 3 days if cured

Q: I am an engaged person who was one day sick, but then recovered, all praise be to Allah Alone. During my illness, my fiancée made a vow to observe Sawm (Fast) for three months if I recovered. Is there any Kaffarah (expiation) for such a vow? What is it? If there is no Kaffarah for this, is it permissible to divide the whole period of three months of Sawm to several small periods? (Part No. 23; Page No. 371

A: It is Wajib (obligatory) on your betrothed to fulfill her vow for it is authentically reported that the Messenger of Allah (peace be upon him) said: Whoever vows to obey Allah, has to obey Him. If your fiancée specified certain months or intended to observe Sawm for the whole period on a successive basis, it is Wajib on her to do exactly as she vowed. Otherwise, it will be permissible for her to observe Sawm of ninety separate days whenever she is able to do so without being required to make any Kaffarah. Finally, we advise your fiancée not to make any vow in the future as the Prophet (peace be upon him) forbade people from making vows. He (peace be upon him) said: It does not 'necessarily' bring good 'in the form of substantial, and tangible results', but it is the means whereby something is extracted from miserly persons. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.