Does the reward for congregational prayer change depending on the extent to which the worshiper comprehends it, and is the congregational prayer counted for one who caught the imam in the final tashahhud, regardless of the reason for the delay?

There is a distinction between the essence of the virtue of congregational prayer and the fruits of congregational prayer. According to the majority of scholars, catching one unit (rak'ah) of the prayer with the Imam is considered catching the essence of the prayer and its virtue, with the worshipper completing their prayer after the Imam’s salutation. Some believe that the virtue of congregational prayer is attained by catching the opening takbir before the Imam’s taslim, while others hold that it is only attained by catching a full rak'ah.

As for the fruits of congregational prayer, they vary. One who joins the prayer from its beginning attains more good than one who joins in its latter part, as rewards differ based on what one catches of the prayer. Thus, one who catches the opening takbir is not like one who misses it, and one who is present for the recitation of Al-Fatihah is not like one who misses that, even if they attain the essence of the virtue of congregational prayer.

If the delay in joining congregational prayer is due to a legitimate excuse, Allah Almighty bestows His favor upon the latecomer with the full reward, as if they had attended the prayer from the beginning, and this does not diminish the reward of those who prayed anything. However, one who delays due to negligence loses some of the reward. Virtues are not measured, and deeds are recompensed according to intentions.