Fatwa no.
18492
Q: When my sister was sick, my mother made a vow saying, "In sha’a-Allah (if Allah wills), I will observe Sawm (Fast) for two days every month if Allah restores my daughter to health." She has observed Sawm for two days every month. However, she feels thirsty and shivers when she fasts. Rather, she feels feeble on observing Sawm. It is worth mentioning that my mother is over sixty years old. What should she do?
A:
It is not obligatory for your mother to observe such Sawm as she stated
the Will of Allah as a condition of fasting.
May Allah grant us success! May peace and blessings be upon our Prophet Muhammad, his family and Companions!
Permanent Committee for Scholarly Research and Ifta'