preferable in our view, whereas anyone who experiences such misgivings only from time to time should proceed on the basis of his certainty.

Whoever is sure of a matter must act upon that certainty in his prayer and not abandon it for what others may tell him; but if he himself becomes doubtful, he should refer the matter to someone whose word he trusts.

If a worshipper omits a prostration in the very first cycle of his prayer and then remembers, he should immediately go down in prostration—provided he has not yet settled into the bowing of the second cycle—and afterwards perform the two prostrations of forgetfulness after the salām. Should he recall it only after having come to rest in the bowing of the second cycle, he is to disregard the missed prostration, begin a new cycle in its place, and count himself as though he has only now entered the prayer.

Some have said that he may still drop to prostration even after settling into that second cycle, so long as he has not yet raised his head from the bowing. If a person forgets a prostration in some cycle—without knowing which one—and remembers this near the end of his prayer, Ibn al-Qāsim holds that he should prostrate, stand, add a full cycle, and then perform the prostrations of forgetfulness after the salām; according to Ashhab, adding just that one cycle is sufficient.

Should someone forget part of an obligatory prayer and then begin a voluntary one, he must return to the obligatory prayer, complete what he missed, and prostrate after the salām—so long as he has not yet bowed in the voluntary prayer or lengthened its recitation. If he has done either, he must repeat the obligatory prayer. It is reported from Mālik that he should still go back to the obligatory prayer even if he has already bowed in the voluntary.

Whoever joins the imām in an obligatory prayer while still engaged in a voluntary one must end the voluntary with salām as soon as he remembers, then commence the obligatory prayer at once. If he continues until finishing with the imām, he must repeat the prayer.

As for someone who performs tayammum during the prayer, our scholars have three opinions: (1) he should make the prostrations after the salām; (2) he should make them before it; (3) nothing at all is required of him.

If a person, after pronouncing the opening takbīr with the imām, becomes inattentive through drowsiness, distraction, or crowding and fails to bow until the imām has already bowed and prostrated—and that