Some scholars have gone so far as to say that if someone other than the mosque’s regular imam leads its congregation without the imam’s permission and without a legitimate legal excuse, the prayer of that congregation is invalid. This shows how serious the matter is and that it must not be taken lightly. The worshippers must respect the rights of their imam and not encroach on his prerogative, just as the imam must respect the rights of the congregation and not place them in difficulty.

Each side, then, should honor the other’s rights so that harmony and affection prevail between imam and congregation. If the imam is late and the time for prayer is running short, they should proceed with the prayer, following the precedent set by Abu Bakr al-Siddiq and ʿAbd al-Rahman ibn ʿAwf (may Allah be pleased with them). When the Prophet was absent on his way to the clan of Banu ʿAmr ibn ʿAwf to reconcile them, Abu Bakr led the people in prayer; and on another occasion when the Prophet was delayed, ʿAbd al-Rahman ibn ʿAwf led them. The Prophet joined him for the final rakʿah, completed the prayer, and then said, “You have done well.”

Another ruling concerning congregational prayer is that a person who has already prayed and then hears the iqama being given in the mosque is recommended to join that congregation for the same prayer. Abu Dharr reported: “Pray the prayer at its prescribed time; but if the prayer is established while you are in the mosque, then pray with the people and do not say, ‘I have already prayed, so I will not pray.’” Muslim related this narration.