What is the ruling on a follower not following his imam if the imam omits the first tashahhud due to forgetfulness?

Question:
He says: Honorable Shaykh, may Allah grant you success, if the follower is certain of his imam’s mistake and does not follow him in that mistake, does he prostrate with him for forgetfulness? For example, if the imam omits the first tashahhud, does the follower not follow him?

Answer:
No, it is not permissible for the follower to leave it. Even if the imam omits the first tashahhud, the follower must follow him, as has been mentioned to you. He does not follow him only if the imam adds to the prayer, such as adding a rak'ah while knowing it is extra; in that case, he does not follow him. As for omitting the first tashahhud, if the imam and the follower are certain that he did not perform the first tashahhud, and the imam does not return to it, the follower follows him and prostrates with him for forgetfulness. Yes.