The reason for not following the imam in the extra rak'ah

This is also a message addressed to you personally. Its sender, the presenter and student 'Abd al-Wahhab 'Umar al-Murayhi at the Juf Scientific Institute, says: Your Eminence, Shaykh 'Abd al-'Aziz ibn 'Abd Allah ibn Baz, the respected General President of the Department of Islamic Research and Ifta, and of Da'wah and Guidance. I ask Your Eminence to answer the questions via the "Light on the Path" program. They are: First: Why did the jurists insist on not following the imam in the extra rak'ah, while the marfu' hadith establishes following the imam and not differing from him in forgetfulness? Among these is what the two Imams narrated in the Sahihs from Abu Hurayrah, which establishes following the imam in forgetfulness, even in the extra rak'ah, as in his statement (peace and blessings be upon him): to the end. And the second hadith: We ask Your Eminence to inform us fully about what we inquired about?
Answer: It has been established by explicit text and scholarly consensus that the prayers have a known number, with no addition or reduction. The Zuhr prayer is four for the resident who is not traveling, and the 'Asr prayer is likewise, and the 'Isha' prayer is likewise, the Maghrib prayer is three, the Fajr prayer is two, and the Jumu'ah prayer is two. So it is a prayer with a known number. If the imam adds a rak'ah, he is either forgetful or intentional. It is not conceivable that a person would add it intentionally unless he is someone who does not know the rulings and does not know what he is doing. The reality is that it is forgetfulness. So if he adds a rak'ah in forgetfulness, he is reminded. If he notices and returns and sits, praise be to Allah. If he does not notice and persists in the addition, then it is obligatory for the one who knows of the addition not to follow him; because this is following in error, and we are commanded not to follow the imams in error, . So the imam is followed, but only in what is right, not in error. The addition that the imam adds in forgetfulness is considered an error and an addition to the legislated prayer. So whoever knows it and knows that it is an error does not follow him, but sits. He does not follow him in the fifth rak'ah of Zuhr, 'Asr, and 'Isha', nor in the fourth of Maghrib, nor in the third of Fajr and Jumu'ah, but he sits.
As for the one who does not know that it is an addition, he follows him in accordance with the hadith mentioned by the questioner: the hadith. This is followed by the ignorant person, the one who did not know about the addition, he follows him; because the original ruling is the obligation of following. As for the one who knows that it is an addition, he has known that it is an error, so he does not follow him in the error, but sits and does not follow him in the error. I do not know of any scholarly disagreement among the people of knowledge that the one who knows that the imam added a rak'ah should remind him by saying: Subhan Allah! Subhan Allah! If the imam responds and returns to the correct path, otherwise it is obligatory for the one who knows that it is an addition to wait. It is obligatory for him to sit and not follow him in the error. This is the well-known position among the people of knowledge, and it is in accordance with the Shari'ah evidence: "Obedience is only in what is right." So there is no one who is obeyed in sins, ever, nor in errors. So if you know that he has erred, do not follow him in the error.
As for the imam who persisted and did not return, he is between two things:
If he believes that what he did is valid and that he is the one who is correct, and that those who reminded him erred, then he has done well and there is no harm on him, if he believes that he is correct. He completes his prayer on his intention and his belief, and his prayer is valid. And those who believed that it was an addition, their prayer is also valid, and there is no blame on all of them. Everyone is judged by his belief and what he knows to be correct in his own view.
As for if he does not have certainty, but he persisted without certainty, then he has erred, and it is not permissible for him to do so; because he persisted in the error. So this addition of his, and he was reminded by two or more of the ma'mum that it is an error, and he does not have certainty, it becomes an error. So his action is not correct, and this addition invalidates his prayer; because he intentionally added a rak'ah that is not legislated. So he added to the prayer intentionally what is not part of it, so the prayer is invalidated by that. As for those who separated from him and sat because they believed it was an addition, their prayer is valid. They complete their prayer, recite the tashahhud, complete their prayer, and say the taslim. As for him, if he does not have insight but he persisted in the error and did not comply with those who reminded him from the congregation, if they were two or more, then his prayer is not correct. He must repeat it from the beginning because he persisted in the invalid and the error without guidance. As for if he is correct; he believes that he is correct and that those who reminded him erred, then this is like what was mentioned before, his prayer is valid, and he is responsible for his belief and there is no blame on him. Yes.
The presenter: But we remain in the taslim, O Shaykh. Do they say the taslim while he has not said it?
The Shaykh: If he persisted and did not return, the best for them is to wait for him. This is the best. And if they say the taslim, it suffices, it is valid; because they are excused by separating. But if they wait for him, it is better; because he may be excused. He may believe in the correctness of himself and be excused. So if they wait for him and say the taslim with him, it is better. Yes.