What is the ruling regarding the congregational prayer of travelers and residents led by a traveling imam, then one of the residents is put forward due to an unexpected circumstance befalling the imam, and how do they complete their prayer?

It is permissible for a resident to pray behind a traveler, and upon him is to complete his prayer after his imam's salutation. It is permissible for a traveler to pray behind a resident and to complete his prayer without shortening it, as long as he has prayed behind him, even for a part of the prayer. If a traveler prays behind a resident imam, he must complete his prayer. There is a disagreement within the Maliki school of thought, where some scholars believe that the traveling congregant in this case does not complete his prayer; rather, he gives the salutation when the successor completes the prayer of the first imam, or he waits for him to give the salutation and gives it with him.