The ruling on responding to the call to prayer for one who hears it

Q: I was a guest at the home of some of my brothers, and I caught up with them for the 'Asr prayer. I asked them if the mosque was far or near, and they answered that it was a little far. They said it would be better for us to pray in congregation at home. However, I feared that it might be close and that I could go to the mosque, but my brothers would be scattered; some would come with me and some would not. Therefore, I prayed with them at home and they made me lead them. Due to the narrowness of the room, one of them prayed to my right.
Is our prayer valid in this situation? If the answer is no, do I repeat only that prayer, or do I repeat every prayer I have prayed since then? Please inform us, may Allah reward you.

A: The prayer in this situation is valid. However, if the mosque is far and they cannot hear the call, there is no blame on them for praying in their place. But if they can hear the call without a loudspeaker, it is obligatory for them to go to the mosque; because of his saying (peace and blessings be upon him): .
Therefore, it is obligatory for every Muslim to respond to the call if he can hear it. But if he cannot hear it except through a loudspeaker, it is not obligatory for him to go to the mosque. If he goes, that is better and more excellent.