What should a person do if the imam stands up for the fifth rak’ah in a four-rak’ah prayer?

If a four-rak’ah prayer is performed as five rak’ahs,
1. What should the imam leading the prayer do?
2. What should the congregation that performs the prayer as five rak’ahs by following the imam do?
3. Is it permissible not to follow the imam when he stands up for the fifth rak’ah and salute individually or to wait for the others by sitting and salute with the congregation?
4. Does the decree change in fard and sunnah prayers or based on time?

Dear Brother / Sister,

A person who stands up for the fifth rak'ah:

If a person stands up by mistake after sitting (tashahhud) in the fourth prayer and if he remembers it before he prostrates, sits down again and salutes, his prayer is valid but he has to perform prostration of forgetfulness (sajda as-sahw). If he remembers it after he prostrates in the fifth rak'ah, he must not sit down but complete the sixth rak'ah and then perform prostration of forgetfulness. According to some scholars, it is not necessary to perform prostration of forgetfulness in this case. However, it is regarded as better to perform prostration of forgetfulness. Fatwa is based on this view. It is also the preferred view. The two rak'ahs that are added are regarded as supererogatory (nafilah) prayer. This is the right view; it is stated in Jawhara an-Nayyira.

If a person stands up for the fifth rak'ah after the fourth rak'ah of the afternoon prayer by mistake and prostrates, he should not add the sixth rak'ah according to some scholars because there is no legitimate supererogatory prayer after the fard prayer of the afternoon prayer. According to the leading scholars, he should add the sixth rak'ah because it is not a deliberate addition. Therefore, it is not regarded makruh.

To stand up without sitting long enough to recite tahiyyat at the end of the prayer:

If a person stands up for the fifth rak'ah at the end of the prayer without sitting long enough to recite tahiyyat and remembers it before he prostrates, he should sit down, sit long enough to recite tahiyyat, utter salutation and perform prostration of forgetfulness. If he prostrates in the fifth rak'ah, he should add another rak'ah according to some scholars; the last two rak'ahs are regarded as supererogatory.  He has to perform the fard prayer, which has been invalidated, again; the same thing is valid for the afternoon prayer because one can perform legitimate supererogatory prayers before the afternoon prayer. There is no drawback to invalidate a fard prayer and transform it into a supererogatory prayer. The fard prayer of the morning prayer is not like that. If a person stands up for the third rak'ah and prostrates, his prayer is invalidated; and the three rak'ahs that have been performed are not regarded as supererogatory.

This is the view of Imam Abu Hanifa and Imam Abu Yusuf. He is free to add the sixth rak'ah or not. The prayer that is invalidated is transformed into a supererogatory prayer.

If a person makes a mistake while performing a two a rak'ah prayer, performs prostration of forgetfulness, stands up without salutation and performs two more rak'ahs, it is valid; however, he needs to return the prostration of forgetfulness. This is the preferred view. The state of a traveler is like that too:

If a traveler performs prostration of forgetfulness because it is necessary after a prayer of two rak'ahs and then intends to be a resident before salutation, he needs to perform two more rak'ahs and completes his prayer by returning the prostration of forgetfulness.

If the imam makes a mistake after the last sitting and stands up for the third or fifth rak'ah as an extra rak'ah after the fard prayer, the congregation should not stand up. If the imam sits again as a result of the warning of the congregation, the prayer is valid but it is necessary to perform prostration of forgetfulness. If the imam has prostrated after the extra rak'ah, the congregation should not follow the imam; they should utter salutation before the imam prostrates. If the imam stands up before the last sitting and prostrates after the extra rak'ah, the prayer of both the imam and the congregation are invalidated.

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