Sahih Muslim

Abu Huraira reported:The Messenger of Allah (ﷺ) while teaching us (the principles of faith), said: Do not try to go ahead of the Imam, recite takbir when he recites it, and when he says: ""Nor of those who err"" you should say Amin, bow down when he bows down, and when he says: ""Allah listens to him who praises Him"" say: ""O Allah, our Lord, to Thee be the praise