What is the ruling if someone vows to fast the entirety of Ramadan by saying, 'For Allah, it is upon me to fast Ramadan'?
General Chapter
Al-Mughni
Book of Vows
Primary text
According to the apparent implication of Al-Khiraqi's position, the vow is valid, and the fast fulfills both the obligation of Ramadan and the vow, making expiation obligatory if the commitment is broken. This is supported by the principle that a vow functions as an oath (Yamin), and thus it takes effect over an obligatory act, necessitating expiation, similar to swearing by Allah Almighty.
Supporting text
The opinion held by Al-Qadi states that the vow does not take effect. This is also the position of Al-Shafi'i, because the fast cannot be accepted as fulfillment of the vow, making it analogous to the night (when fasting is invalid).