Assalam’alaikum,
I always performed congregation fajr prayers at a mosque in our local neighbourhood. As the imam is from Shafe’i Mazhab, he would always raised his hands and recited the qunut duas. Since my understanding that there is no qunut in fajr prayers, I would remained still without raising my hand when the imam was reciting the qunut.
One morning the same imam forgot to recite the qunut duas. However, he performed the sujud sahwi before ending the prayers. I believed that there was no defect in my prayers even though the imam had forgotten to recite the qunut. However, in such situation, must I follow the imam in the performance of the sujud sahwi ?
Thank you.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

First of all, if you mean by your statement “I would remain without raising my hands when the Imaam is reciting Qunoot” that you also make Qunoot with him but without raising your hands, we hope that this is permissible, as the Shaafi‘i scholars of Fiqh have two famous opinions about raising hands while reciting Qunoot: the first is that it is undesirable, and the second, which is the sound opinion, is that it is desirable.

But if you mean by it that you do not make Qunoot with the Imaam, then you should know that you have to follow your Imaam in making Qunoot even if you do not see it legislated, as stated by scholars .

Shaykh Al-Islam Ibn Taymiyyah said about the Imaam's Qunoot in the Fajr prayer, after showing that to practice Qunoot constantly in Fajr prayer is not a Sunnah: "However, whoever believes in that, depending on his own Ijtihaad (a juristic opinion on matters which are not specified in the Quran and the Sunnah), then his Ijtihaad is acceptable as is the case in all other matters of Ijtihaad. For this reason, the one led in prayer should follow his Imaam in matters in which Ijtihaad is acceptable. So, if the Imaam practices Qunoot, he should practice Qunoot with him, and if the Imaam leaves it, he should not practice Qunoot (without him). The Prophet, sallallaahu ‘alayhi wa sallam, said: "The Imaam is made to be followed." He further said: "Disagree not with your Imaams." It is also proven in an authentic Hadeeth that he, sallallaahu ‘alayhi wa sallam, said: "They (your Imaams) lead you in prayer: if they do right it (the reward) would be for you and them; and if they commit a mistake, it (the reward) would be for you, and (the sin would be) on them.""

Al-Buhooti (from the Hanbali School of Fiqh that does not opt for the permissibility of Qunoot in Fajr prayer) said that Ibn Taymiyyah said in his “Al-Ikhtiyaaraat”: "And if the Imaam does things in which Ijtihaad is acceptable, the one led in prayer should follow him, even if he himself does not believe in it, such as Qunoot in Fajr prayer..."

Therefore, the Imaam offers prostration of forgetfulness before Tasleem for leaving Qunoot forgetfully, the one led in prayer should follow him, for the general pieces of evidence that command people to follow the Imaam and not to disagree with him. Ibn Qudaamah said in his “Al-Mughni”: "And if the Imaam forgets something in prayer, the one led in prayer should follow him in offering the prostration of forgetfulness, whether he also has forgotten or it was only the Imaam who has forgotten. According to Ibn Al-Munthir, : "There is consensus on that among all the scholars from whom we take knowledge."

An-Nawawi said in his “Al-Majmoo'": "And if he (the one led in prayer) does not follow him (the Imaam) intentionally, his prayer would be rendered invalid. It is the same whether or not the one led in prayer knows what the Imaam has forgotten; whenever the Imaam offers two prostrations (of forgetfulness) at the conclusion of his prayer, it becomes binding upon the one led in prayer to follow him."