Is making up the fast obligatory if one eats believing dawn has not broken when it has, or breaks the fast believing the sun has set when it has not?
General Chapter
Al-Mughni
Book of Fasting
Primary text
Making up the fast is obligatory if one eats believing dawn has not broken when it has already broken, or breaks the fast believing the sun has set when it has not. This is the position held by the majority of scholars from the jurists and others. The evidence supporting this is that the person ate intentionally while remembering the fast, thereby breaking it, similar to one who eats on the Day of Doubt. Additionally, they were ignorant of the time for fasting, and this ignorance does not excuse them, just as ignorance of the start of Ramadan is not an excuse. It is also possible to guard against such an error, resembling the action of one who eats intentionally, unlike the forgetful person, who cannot guard against forgetfulness.
Supporting text
It is related from Urwah, Mujahid, Al-Hasan, and Ishaq that no makeup fast is required for such an instance. This is based on a narration where companions, believing it was still night in Ramadan during the time of Umar ibn Al-Khattab, drank something; when the sun appeared, some suggested making up the day, but Umar stated, 'By God, we will not make it up; we did not incline toward sin.' They argue that since the eating was not intended as breaking the fast, making it up is not required, similar to the forgetful person.