Chapter: The Prostrations of Forgetfulness

Performing these prostrations is recommended when, by mistake, one utters a prescribed statement in an improper place; it is permissible when a sunnah element has been left out; and it is obligatory whenever an extra bowing, prostration, standing, or sitting—even as brief as the sitting of rest—is added, or when the salām is given before the prayer is finished, or a recitational error occurs that changes the meaning, or a required element is omitted, or there is doubt, at the time, about having added something.

The prayer becomes invalid if one deliberately omits a prostration of forgetfulness that is obligatory, but not3 when the obligation arose because the salām was uttered before the prayer had been completed.

One may perform the two prostrations of forgetfulness either before the salām or after it; however, if they are performed after it, one must sit for the tashahhud and then give the salām.

If the prostrations are forgotten until an interval customarily deemed long elapses, or ritual impurity is incurred, or the person leaves the mosque, the obligation lapses.

A follower who joined4 the prayer from the very start is not required to perform a prostration for a mistake that was his alone.