question #1 Sahih Muslim 416, Book 4, Hadith 96 : What is the significance of the Imam in leading prayers according to Islamic teachings?

The Messenger of Allah (ﷺ) said: Verily the Imam is a shield, say prayer sitting when he says prayer sitting. And when he says:” Allah listens to him who praises Him,” say:” O Allah, our Lord, to Thee be the praise.” and when the utterance of the people of the earth synchronises with that of the beings of heaven (angels), all the previous sins would be pardoned.