fasting twice, except when the worshipper has been negligent. Where there has been no negligence, Allah has not required two months of fasting in a year or two noon prayers in a day. This demonstrates the weakness of the view that requires someone both to perform a prayer and to repeat it. This is a weak principle, as has been discussed at length elsewhere. It includes requiring someone to pray behind an openly sinful imam and then repeat the prayer; to pray despite rare impediments that do not persist and then repeat the prayer; or requiring a woman experiencing non-menstrual bleeding to fast twice. Such rulings are found in the schools of al-Shāfiʿī and Ahmad, according to one of the two views.

The correct position, held by the majority of Muslims, is that whoever performs an act of worship as commanded, to the best of their ability, need not repeat it. As Allah Most High says:

“So fear Allah as much as you are able.”

It has never been known that the Messenger of Allah, may Allah bless him and grant him peace, commanded anyone to perform the same prayer twice. Rather, he would command someone to repeat it if they had failed to do what they were commanded despite being able to do so. Thus, he said to the man who prayed incorrectly:

“Go back and pray, for you have not prayed.”

Likewise, he commanded the man who prayed alone behind the row to repeat his prayer.

As for those with a valid excuse—such as someone who performs dry ablution because water is unavailable, or because using it could cause harm due to illness or cold; a woman experiencing non-menstrual bleeding; and others like them—the Sunnah of the Messenger of Allah, may Allah bless him and grant him peace, is that they do whatever they can, according to their ability, while whatever lies beyond their ability is waived. Indeed, his Sunnah regarding someone who was unaware of an obligation is that there is no requirement to make it up