An Imam (the one who leads congregational

A: Firstly: The Imam does not have to perform Sujud-ul-Sahw if he is sure of the correctness of what he has done. He is not permitted to respond to those who say, "Subhan Allah," if he thinks that they are mistaken. However, if the Imam is not sure that what he has done is correct, it is obligatory on him to sit down in response to them, because what he has stood up for is an additional act and he is not permitted to continue in it.Secondly: The Ma’mums who know that he has stood up to offer an extra Rak‘ah, a fifth Rak‘ah in a four-Rak‘ah Salah (Prayer consisting of four units) for example, should draw the Imam’s attention to it by saying, "Subhan Allah." If the Imam does not respond, they should remain sitting and wait for the Imam to say the Taslim and say it after him. Accordingly, the Salah of those who remained sitting and said the Taslim after the Imam was correct. On the other hand, those who stood with the Imam and followed him, while knowing that it was an extra Rak‘ah and were cognizant of the Shar‘y (Islamic legal) ruling that it was not legitimate to follow him in this situation, their Salah was Batil, as they were not permitted to follow him in that, and they should repeat their Salah. (Part No. 6; Page No. 17) Those who thought that the Salah was not complete or had doubts as to whether their Salah was complete or deficient should follow the Imam to complete their Salah with him.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.