Sahih Muslim, 935

Rapporté par Abu Huraira رضي الله عنه : Le Messager d’Allah ﷺ a dit : « L’imam est désigné pour être suivi. Dites le takbir quand il le dit, inclinez-vous quand il s’incline, et quand il dit : “Allah entend celui qui Le loue”, dites : “Ô Allah, notre Seigneur, à Toi la louange.” Quand il prie debout, priez debout, et quand il prie assis, priez tous assis. »

Abu Huraira reported Allah's Messenger (ﷺ) saying:The Imam is appointed to be followed. So recite takbir when he recites it, and bow down when he bows down and when he utters:" Allah listens to him who praises Him," say" O Allah, our Lord, for Thee be the praise." And when he prays, standing, you should pray standing. And when he prays sitting, all of you should pray sitting