What is the ruling on fulfilling a vow to fast if the arrival day is Eid al-Fitr or Eid al-Adha?
General Chapter
Al-Mughni
Book of Vows
Primary text
There are differing narrations from Ahmad regarding fasting on the arrival day if it falls on Eid al-Fitr or Eid al-Adha. One narration holds that the fast is not observed; the person must make it up (qada') and offer the expiation (kaffara) of an oath. This is the position of most of his companions, Al-Hakam, and Hammad. A second narration states that the person must make it up without expiation, supported by Al-Hasan, Al-Awza'i, Abu Ubayd, Qatadah, and Abu Thawr, based on the reasoning that the obligatory fast was missed due to a valid excuse (divine prohibition), making it like missing a fast due to forgetfulness, thus requiring qada' but no kaffara.
Supporting text
A third narration from Ahmad holds that the fast is valid if performed, which aligns with the view of Abu Hanifa, likening it to fulfilling a prohibited vow where the act itself is permissible. Another possibility suggests kaffara without qada', as the day made the fast forbidden, similar to a woman vowing to fast during menses. A final position suggests neither qada' nor kaffara, based on the principle applied to vowing disobedience. Al-Kharqi's view is that the vow is valid, requiring qada' due to the valid excuse, and kaffara due to its omission, similar to missing due to illness.