What is the ruling on making up a fast for a sick person who endures and fasts despite being permitted to break the fast?
General Chapter
Al-Mughni
Book of Fasting
Primary text
There is scholarly consensus on the permissibility of breaking the fast for a sick person in general. The basis for this is the Quranic verse: "But whoever is ill or upon a journey, then an equal number of other days [are required for fasting]" (Quran 2:184). The illness that permits breaking the fast is severe illness that either increases due to fasting or is feared to slow recovery. If a sick person endures fasting despite being in a condition where breaking the fast is permitted, they have performed a disliked act because it involves self-harm and neglecting Allah's concession. However, their fast is valid and fulfills the obligation, as it concerns an act where leaving the obligation is permitted by concession; thus, if one undertakes it resolutely, it counts, similar to a sick person attending Jumu'ah when permitted to stay away, or standing in prayer when permitted to sit.
Supporting text
It is narrated that if a sick person does not have the capacity to fast, they should break their fast. Regarding what constitutes sufficient illness, it was stated that fever qualifies, and certainly, no illness is more severe than fever. Some early Muslims permitted breaking the fast for any illness, even a toothache or finger pain, due to the general nature of the verse and the fact that a traveler is permitted to break the fast even if not strictly necessitated, implying the same for the sick.