Any fast he might observe would not be valid; if, however, he repents during the month, he must fast the remaining days, and he is not required to make up the days missed while he was in a state of unbelief.

Fasting is not obligatory for a minor, yet the fast of a discerning child is valid and, for him, counts as a voluntary act.

Nor is the fast obligatory for someone who is insane; even if he were to fast in that condition, it would not be valid, for he lacks intention.

Likewise, a sick person who is unable to fast and a traveler are excused from fasting during the month; they must make up the missed days once the excuses of illness or travel have ended. The Exalted says: “But whoever among you is ill or on a journey shall fast a number of other days” (Q 2:184).

The command to fast embraces the resident and the traveler, the healthy and the sick, the ritually pure as well as the menstruating and postpartum women, and even one who is unconscious. All of them carry the duty of fasting in their legal liability: they are addressed so that they acknowledge its obligation and resolve to fulfill it, whether by performance in the month itself or by making it up later.

One group is required to fast the month itself—namely the healthy resident—except for the menstruating and postpartum women. Another group is addressed only with making it up: the menstruating woman, the postpartum woman, and the sick person who cannot fast now yet is able to make it up later. A third group is given the choice between the two options: the traveler and the sick person who can fast, though only with hardship and without fear of serious harm.