when he remembers it. The same applies to any obligatory acts of the prayer that he forgets: he must perform them when he remembers, either as a supplement to the prayer or by beginning the prayer anew. One is not discharged from the obligation of the prayer, or of its obligatory components, except by performing them.

As for obligatory acts that are said to be waived through forgetfulness, such as the first tashahhud, no one has said that they are waived without a substitute. Rather, they are replaced by the prostrations of forgetfulness, unlike the essential elements, such as bowing and prostration, for which there is no substitute. As for saying that these acts are obligatory within the prayer yet may be waived without a substitute, we know of no one who has said this. If anyone has, it is a weak view contrary to the established principles.

These, then, are two views concerning the prostrations obligatory before the closing salutation when they are omitted out of forgetfulness. The disagreement concerning those obligatory after it is similar.

Many of those who regard them as obligatory incline to the view that omitting them does not invalidate the prayer. This is because they remedy a deficiency in an act of worship while remaining external to it, so their omission does not invalidate that act, just as with the compensatory acts for Hajj. However, a report from Ahmad indicates that the prayer is invalidated if one omits the prostrations prescribed after the closing salutation. Al-Athram also reported that Ahmad withheld judgment on this question. Regarding someone who forgot the prostrations of forgetfulness, Ahmad was reported to have said:

“If it concerns a minor instance of forgetfulness, I hope that nothing is required of him.”

I said, “What if it concerns something in which the Prophet, peace and blessings be upon him, himself forgot?”

He said, “Ah,” but gave no answer.

He said, “I subsequently heard that he considered it recommended to repeat it.”

In such “questions on which he withheld judgment,” his followers derive two legal positions.