As for doubt, the position of the school (1) is that doubt is a single category: one bases one’s prayer on certainty—that is, the lesser number—and performs the prostration of forgetfulness before the salām. Thus, there is no case in which one acts on what is more likely; even if one of the two possibilities appears more likely, one still bases the prayer on certainty. Whenever one bases the prayer on certainty, the prostration is to be performed before the salām.

However, the correct view indicated by the sunnah is that doubt is of two types:

1. Doubt in which one of the two possibilities is more likely: one acts upon what is more likely, bases the prayer on it, and performs the prostration after the salām.

2. Doubt in which neither possibility is more likely: one bases the prayer on certainty and performs the prostration before the salām. This was the view preferred by Shaykh al-Islam.

The second issue we learn from the author is that the prayer is invalidated if one omits the prostration whose proper place is before the salām, but it is not invalidated if one omits the prostration whose proper place is after the salām. The difference between them is that the prostration whose place is before the salām is obligatory within the prayer, since it is performed before leaving it; whereas the prostration whose place is after the salām is obligatory for the prayer, since it is performed after leaving it. What invalidates the prayer when deliberately omitted is that which is obligatory within the prayer, not that which is obligatory for it. Thus, if one deliberately omits the first tashahhud, one’s prayer is invalid, because it is obligatory within the prayer. But if one deliberately omits the iqāmah for the prayer, one’s prayer is not invalid, because the iqāmah is obligatory for the prayer; and likewise, according to