Is it obligatory for the ma'mum (one praying behind the imam) to see the imam in prayer?

Question : Is it obligatory for the follower to see the imam in prayer? And what is the ruling if there is a separating wall between them?

Answer : If the ma'mum is in the mosque, it is not required that he see the imam, nor that he see those behind the imam, provided he can follow along by sound. For example, if we have a mosque with a lower level, what do they call it? A basement, a cellar, a private room, a fourth name, a squirrel? In any case, if there is a private room in the mosque, or a basement, or a tunnel, or a passage—God guide you, I don't know about passages in the mountains—in any case, if there is a private room where the person inside cannot see the imam and cannot see any of the ma'mum, but he can hear the sound, there is no harm, because this place is part of the mosque; I mean, this place is part of the mosque. As for if he is outside the mosque.
If he is outside the mosque, some scholars said that if he hears the sound and sees the imam or the ma'mum, there is no harm. And some people of knowledge said no. It is not permissible for one who is outside the mosque to follow the imam unless the rows are connected and the people have filled the mosque and then spilled out into the streets; in that case, there is no harm, because this congregation is gathered around one imam. But if he is in another place, it is not valid for him to be a ma'mum behind the mosque's imam, whether he sees the imam or sees the ma'mum. And this is the stronger opinion, because what is intended by the congregation is what? That the people gather in one place, have one appearance, bond with one another, and get to know one another. If we opened this door and said that whoever sees the imam or the ma'mum, even if he is outside the mosque, may follow the imam, if we opened this door, a great door of evil would open for us. What is it? That people would follow via television. In the Grand Mosque.
Is that not so? A person comes to his house, and he has children, it is Friday, and he is in the Eastern Region, for example, far from the Grand Mosque, and he turns on the television and hears the imam. When he hears, what does he hear? He hears the imam directly and sees him directly. We told him to pray, and he said, "Praise be to Allah, I am praying now with a congregation larger than your mosque." What is the congregation? The Grand Mosque, and the place of those I am following is better than your place. So I and my children are with me, and I did not stand alone in a row; I arranged myself and them and put the television in front of us. Whenever the imam says Allahu Akbar, we say Allahu Akbar; whenever he bows, we bow; whenever he prostrates, we prostrate. And in that case, the Friday prayer in the mosques becomes nullified, and this is a major condition. Therefore, we hold that it is necessary for the imam and the ma'mum to be in agreement regarding the place. It is necessary, except in one case I mentioned to you. What is it? If the mosque is filled and the rows are connected, then even if you go a mile or two miles, because the congregation is now considered one congregation. Now the brothers are pointing with their fingers that the time is up. I know, be patient. Wait, my brothers. Wait, wait, Adel. May Allah reward you with good. It appears that you are the one who started this on us. Please, let it be, young men. Look, may Allah bless you.