Is the first congregational prayer in the mosque obligatory, or is congregational prayer in the mosque obligatory, or is congregational prayer obligatory? And is it necessary to go out and look for a congregation if I am alone at home? And when does its obligation cease?

Congregational prayer in the mosque is obligatory, according to the more authoritative view of the jurists, and it is not permissible to miss it without an excuse. So, if you hear the call [to prayer], you must go to the mosque. However, if you are in a place where you do not hear the call, then you are not obligated to seek out a congregation.