When the Imam offers a fifth Rak`ah, the latecomers should make up for what they have missed

Q: I was in a Masjid (mosque), while the Zhuhr (noon) Prayer was being offered. The Imam (the one who leads congregational Prayer) offered four Rak‘ahs (units of Prayer) and then rose up to offer a fifth. Although all the Ma’mums (persons being led by an Imam in Prayer) said Tasbih (Subhan Allah [Glory be to Allah]) [to draw his attention to the mistake he had made], he stood up. One of the Ma’mums spoke and told him that it was a fifth Rak‘ah, but the Imam did not listen and completed it. The Imam and the Ma’mums had an argument, each defending their opinions.My questions are:1. Is it permissible for the Imam to continue the Rak‘ah although the Ma’mums drew his attention to his mistake?2. Is it permissible for the Ma’mum to speak while offering Salah (Prayer)?3. Is a latecomer who misses a Rak‘ah from this congregational Salah considered to have completed the Zhuhr Prayer because of this additional fifth Rak‘ah or should they make up for the Rak‘ah they missed? A: First: It is obligatory for the Imam who forgetfully rises up to offer a fifth Rak‘ah and then it is brought to his attention by the Ma’mums, and he is not sure that what he is doing is correct, to respond to the Ma’mums. (Part No. 6; Page No. 47

A: First: It is obligatory for the Imam who forgetfully rises up to offer a fifth Rak‘ah and then it is brought to his attention by the Ma’mums, and he is not sure that what he is doing is correct, to respond to the Ma’mums. (Part No. 6; Page No. 47) If the Imam intentionally continues offering the fifth Rak‘ah, his Salah will be rendered Batil (null and void) and the Salah of the Ma’mums who follow him in this will also be Batil, if they know that it is a fifth Rak‘ah.Second: Speaking intentionally renders the Salah Batil. However, if the speaker does that unintentionally or forgetfully, it does not nullify it, according to the preponderant scholarly opinion, because of the Hadith narrated by Mu‘awiyah ibn Al-Hakam that a man sneezed while offering Salah in congregation. Mu‘awiyah responded with, "Yarhamuka Allah (may Allah have mercy on you)," but the Sahabah (Companions of the Prophet - may Allah be pleased with them) disapproved of what he did. Thus, when he concluded his Salah, he went to ask the Prophet (peace be upon him), who said: “Truly, nothing of people’s talk is right during this Salah; it is only Tasbih (glorification of Allah), Takbir (magnification of Allah) and recitation of Qur’an.” In addition, the Prophet (peace be upon him) did not order Mu‘awiyah to repeat his Salah. This shows that speaking during Salah does not nullify it if the speaker is ignorant of the legal ruling. Also, speaking for the interest of the Salah does not nullify it, based on the Hadith of Dhul-Yadayn.Third: If someone misses a Rak‘ah of the congregational Salah and the Imam mistakenly offers a fifth Rak‘ah, the late-comer should not count in this additional Rak‘ah and they should make up for the Rak‘ah which they missed.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.