What is the ruling for vowing to fast on Eid al-Fitr or Eid al-Adha?
General Chapter
Al-Mughni
Book of Vows
Primary text
Vowing to fast on the Day of Eid constitutes a vow of disobedience, for which only the expiation (kaffara) is due upon the vow-maker. This is the correct view, as vowing disobedience does not establish obligation for qada', unlike cases where the prohibition arose incidentally.
Supporting text
There is another narration that qada' is due along with kaffara, similar to the previous mentioned case. Furthermore, it can be argued that nothing is due based on the principle applied to vowing disobedience in other contexts. If the vow-maker intended disobedience, the vow is not established, falling under the hadith: 'There is no vow in disobedience.'