Ruling on following the imam from outside the mosque or following a prayer by listening to the radio
Question

                In Ramadaan we saw on TV that some people pray Taraaweeh with the imam of the Haram whilst they are in their homes neighbouring the Haram.
Praise be to Allah.
    Whoever wants to pray in a mosque in congregation has to go 
    to the mosque, because if he follows the imam in his home this is not prayer 
    in congregation, even if he can see the imam and congregation. Shaykh Ibn 
    ‘Uthaymeen (may Allaah have mercy on him) has spoken in detail on this 
    issue. 

    Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said in 
    his commentary on Zaad al-Mustaqni’: 

    The phrase “and the same applies if he is outside and sees 
    the imam or the congregation” means that a person’s following the imam is 
    valid if he is outside the mosque, on condition that he can see the imam or 
    the congregation. The apparent meaning of the author’s words is that it is 
    not conditional upon the rows (of worshippers) being uninterrupted. So if it 
    is assumed that a person is a neighbour of the mosque and he can see the 
    imam or the congregation from his window and he prays in his house, and 
    there is someone with him so that he is not praying alone, then it is valid 
    for him to follow this imam, because he can hear the takbeer and see the 
    imam or the congregation. 

    The apparent meaning of the author’s words is that he has to 
    see the imam or congregation throughout the entire prayer, so that he will 
    not miss following the imam. The view of our madhhab is that it is 
    sufficient for him to see them for part of the prayer. 

    So, if he is outside the mosque, two conditions must be met: 

    1 – That he can hear the takbeer

    2 – That he can see the imam or the congregation, either 
    throughout the entire prayer, according to the apparent meaning of the 
    author’s words, or for part of the prayer, according to the view of our 
    madhhab. 

    The apparent meaning of his words is that it is not essential 
    for the rows (of worshippers) to be uninterrupted, if the person is praying 
    outside the mosque. This is the view of our madhhab. 

    The second view – which is that of the author of al-Muqni’, 
    is that the rows (of worshippers) must be uninterrupted, and that it is not 
    valid for one who is outside the mosque to follow the imam unless the rows 
    are joined to one another, because what counts in congregational prayer is 
    for all the worshippers to be doing the same things at the same time, 
    following one imam in one place. But we say that if the imam and the 
    worshippers are in the same mosque, and there are two other worshippers in 
    another room between which and the mosque there is some distance, and 
    another two in a third room, undoubtedly this is splitting up the 
    congregation, especially according to the view of those who say that prayer 
    in congregation must be offered in the mosque. 

    The correct view with regard to this matter is that it is 
    essential for those who follow the imam from outside the mosque there should 
    be no interruption in the rows; if there is any interruption in the rows 
    then their prayer is not valid. 

    For example: there are buildings around the Haram, in which 
    are apartments in which people pray. Those people can see the imam or the 
    congregation for all or part of the prayer. According to the words of this 
    author, their prayer is valid, but we say to them: if you hear the iqaamah 
    then you can stay where you are and pray with the imam, and not come to 
    al-Masjid al-Haraam. 

    According to the second opinion, the prayer is not valid, 
    because the rows are interrupted. This is the correct view, which refutes 
    the fatwa that stated by some contemporary scholars, that it is permissible 
    to follow the imam in a prayer that is being broadcast. He wrote an essay 
    concerning that, entitled al-Iqnaa’ bi Sihhat Salaat al-Ma’moom khalfa 
    al-midhaa’. This view implies that we need not pray Jumu’ah in the 
    Friday mosques, rather we can follow the imam of al-Masjid al-Haraam, 
    because in that way we will have a larger congregation and that will be 
    better, even though the one who follows a prayer broadcast on the radio 
    cannot see the congregation or the imam, and if it comes by TV which 
    broadcasts the prayer live, it is more likely to be appropriate. 

    But this is undoubtedly a false view, because it leads to 
    abolishing of prayer in congregation and Jumu’ah prayer, and the rows (of 
    worshippers) are interrupted in this case, and it does not achieve the 
    purpose for which the Lawgiver enjoined prayer in congregation and Jumu’ah 
    prayer. 

    The one who follows a broadcast prayer is not praying behind 
    an imam who is in front of him, rather there is a huge distance between 
    them, and this opens the door to evil, because the one who is careless about 
    Jumu’ah prayer could then say that so long as it is valid to follow a prayer 
    broadcast on the radio or TV, then I am going to pray at home, with my son 
    or brother etc, and we will form a row. 

    But the correct view is that it is not valid to follow the 
    prayer outside the mosque unless the rows are uninterrupted, and two 
    conditions must be met: 

    1-That the worshipper can hear 
    the takbeer

    2-That the rows be uninterrupted.
With regard to seeing 
    the imam or congregation, this is a matter that is subject to scholarly 
    debate. But so long as the takbeer can be heard and the rows are 
    uninterrupted, then it is valid to follow the imam. Based on this, if the 
    mosque is full and the rows are uninterrupted, and people pray in the market 
    places and outside shops, there is nothing wrong with that. 

    Al-Sharh al-Mumti’, 4/297-300. 
And Allaah knows best.