what he had missed between the dawn prayer and the noon prayer is, however, governed by other reports that state there is no prayer after Fajr until the sun rises, nor after it has risen until it climbs the height of a spear. Accordingly, the broad wording of the hadith the author cited is qualified by the more specific narration we have mentioned, and the make-up is to be offered once the sun has risen that far.

Some scholars argue that it need not be limited at all, for whenever a person remembers a missed act of worship he should perform it immediately, in keeping with the general statement of the Prophet (peace and blessings be upon him): “Whoever sleeps through a prayer or forgets it must perform it when he remembers it; there is no expiation for it other than that.”

The hadith quoted by the author also teaches that one should persevere in good deeds and should make up whatever he misses whenever it is still possible to do so. As for acts that cannot be made up, once they are forgotten they lapse—such as the Sunnah of entering the mosque, known as the Greeting of the Mosque. If a person enters, forgets, sits down, and a long time passes, he does not make it up, because this prayer is a Sunnah tied to a specific cause, and once the cause is gone its Sunnah lapses. The same rule applies to every act linked to a cause: when the cause disappears it is not to be made up, unless it is an obligatory duty like the prescribed prayers.

By contrast, anything tied to a specific time may be made up if missed, such as the regular Sunnah prayers. Should one forget them until their time has elapsed, he may perform them afterwards, as is firmly established from the Prophet (peace and blessings be upon him).

Likewise, if someone fails to fast the three days of each month—the al-ayyam al-bīd (the “white days”)—he may make them up later, even though fasting any three days of the month is broad in scope; it is permissible