But if the interval between the salām and the correction becomes lengthy, or his ablution is broken, he must start the prayer afresh—unless what was omitted was the final tashahhud or the salām itself. In that case it is not treated as though he had missed an entire rakʿah; rather, he says what he left out, makes the prostration of forgetfulness, and then gives salām.

If he forgets the first tashahhud and rises for the third rakʿah, he is required to return and recite it so long as he has not yet reached a fully upright position; once he has stood completely, it is disliked for him to go back, because he has already engaged in another pillar and should not interrupt it.

If he omits the tasbīḥ while bowing or prostrating, he must return and pronounce it—provided he has not yet straightened up to stand in the next rakʿah—and in all these cases he performs the prostration of forgetfulness.

The third circumstance is doubt during the prayer. If a worshiper is uncertain about the number of rakʿahs—unsure, for example, whether he has prayed two or three—he should build on the lesser number, for that is the part that is certain, and then perform the prostration of forgetfulness before the salām. This rests on the principle that what is doubtful is treated as nonexistent and on the hadith of ʿAbd al-Raḥmān ibn ʿAwf: “If any of you is unsure in his prayer and does not know whether he has prayed one rakʿah or two, let him count it as one; or if he does not know whether it is two or three, let him count it as two,” narrated by Aḥmad, Muslim, and al-Tirmidhī.