What invalidates the Prayer

According to the fatwas of the Grand Religious Authorities: Ayatollah Sayyed Ali Khamenei, Ayatollah Sistani, and Ayatollah Makarem Shirazi (may Allah prolong their blessings):

Fatāwā presented without citing a differing opinion or a specific reference are the common rulings shared by all of the three respected Marāji‘. In cases where the ruling of one Marjaʿ differs from that of the other two, it is indicated in a footnote under the same number, mentioning the Marjaʿ by name.

Types of doubts in Prayer

Doubt means probability of fifty percent. If the probability is more than fifty percent, it is called ẓan (suspicion) and has different rules.

There are three types of doubt¹ in prayer:

1. Doubt about the prayer itself,
2. Doubt about a part of the prayer,
3. Doubt about the number of unit (Rak’ah) one is performing.
4. A) Doubt about the Prayer Itself

If, after the prayer’s time, one doubts having performed it, or feels more than fifty percent sure that they have not performed it, it is not necessary to perform it. However, if before the end of the prayer’s time, one has such doubts, one should perform the prayer. Moreover, if one thinks (i.e., more than fifty percent) that they have not performed it, they should pray again.

Ayatollah Sistani: If, after the time for a prayer has passed, a person doubts whether they performed the prayer or not, or even thinks that they did not perform it, performing it is not needed. But if, before the prayer time has passed, they doubt whether they performed the prayer or not, then—even if they think that they did perform it—they must perform that prayer.

Ayatollah Makarem Shirazi: Whenever, after the time for a prayer has passed, a person doubts whether they performed the prayer or not, or even thinks that they did not perform it, they should not pay attention to this doubt. But whenever, before the prayer time has passed, they doubt, they must perform the prayer; even if they think they performed it, that is not sufficient.

1. b) Doubt about a Part of the Prayer
2. During prayer, if one doubts having performed one of the obligatory acts of prayer and has not yet started the next part, one should perform it; however, if one has started the next part (even if it is a recommended (mustaḥab) part), one should ignore their

Ayatollah Sistani: If, during the prayer, a person doubts whether they have performed one of its obligatory acts or not—for example, they doubt whether they have recited al-Hamd—then if they are engaged in an act that, according to Islamic law, they should not be engaged in if they had deliberately omitted that previous act (for example, they are reciting the surah and doubt whether they recited al-Hamd), they should not pay attention to this doubt. But if this is not the case, they must perform the act about which they are in doubt.

2. If before starting the recitation of  Chapter (Surah) al-Fatihah, including uttering

اعوذ بالله من الشيطان الرجيم

(which means “I seek refuge in Allah from Satan, the rejected one”), one doubts having said the formal prayer opener (takbīrah al-iḥrām), one should say it.

3. If one doubts having recited Chapter (Surah) al-Fātiḥah, if one has not yet started the next part (even though it is a recommended (mustaḥab) part), such as one should recite it

الحمد لله

4. If one doubts having recited the second chapter (surah) and has not yet started the next part, one should recite If one is already bowing (rukū‘) bowing or reciting the special in-prayer supplication (qunūt) or a recommended (mustaḥab) remembrance of Allah (dhikr) after the second chapter (surah), one should ignore their doubt.
5. If before bending down for prostration (sajdah), one doubts having performed the bowing (rukū‘), one must perform the bowing (rukū‘).
6. If before standing up for the second or fourth unit (Rak’ah) or before starting to recite the testament of faith (tashahhud) [the two fundamental pillars of faith], one doubts having performed one or two prostrations (sajdah), one must perform another prostration (sajdah). The same rule applies if one’s doubt occurs while they are rising, i.e., before being in a standing position.
7. Before standing up, if one doubts having recited the testament of faith (tashahhud) [the two fundamental pillars of faith], they should recite However, if this doubt arises while they are standing, or if they have started the next part, even if it is a recommended (mustaḥab) part of the prayer, they should ignore their doubt.
8. A person who doubts having recited the concluding salutation (salām) or not, if one is engaged in saying a supplemental supplication (ta‘qīb) or other prayer, or if one is not in the state of prayer because of something that disrupts the prayer, g., turning away from the direction of prayer (qiblah), one should ignore this doubt; however, if one’s doubts arise before doing these things, one should repeat the concluding salutation (salām).
9. If, while reciting a Quranic verse, one doubts having read the previous verse, or one doubts having read the beginning of a verse while they are reciting the last part of a verse, they should ignore this doubt.
10. If, after performing one of the acts of prayer, one doubts having performed it correctly or not, they should ignore their doubt, regardless of whether or not they have started the next part.
11. If one has doubts about one of the parts of the prayer before starting the next part and performs it, then one realizes that they have performed it twice, so long as that part is not a foundational element (rukn) of prayer, one’s prayer is not invalid.
12. If, after starting the next part, one doubts doing the previous part and ignores their doubt, then realizes that they did not perform that part, if one has not started the next foundational element (rukn), one should perform it and then perform what they had done before by mistake. If one has started or performed the next foundational element (rukn) and the neglected part was a foundational element (rukn), their prayer is invalid. If it was not a foundational element (rukn), the prayer is If the neglected part was prostration (sajdah) or the testament of faith (tashahhud) [the two fundamental pillars of faith], one must perform the missed prostration (sajdah) after the prayer. By way of obligatory precaution, if the neglected part was the testament of faith (tashahhud), one must perform the missed testament of faith (tashahhud) [the two fundamental pillars of faith] followed by two prostrations (sajdah) of inadvertence (sahw).