If one regains sanity during part of a day during Ramadan, must they make up that day's fast?
General Chapter
Al-Mughni
Book of Fasting
Primary text
If sanity is regained during part of the day, it necessitates that the person must make up the missed fast, just as a boy who reaches puberty or a disbeliever who converts during the day must perform the corresponding obligations. If sanity is regained during part of the day, the obligation of fasting for that part is established.
Supporting text
The view holding that it must be made up relies on the principle that since the obligation is prevented when insanity covers the entire day, it is prevented when it covers part of the day, analogous to childhood or disbelief. The comparison to menstruation is rejected because menstruation only permits postponement and forbids performance; it does not prevent the obligation itself in the way that insanity does.