Anas bin Malik reported,

The Prophet ﷺ fell from a horse and injured his right side. The companions came in to visit him, and he led them in prayer while seated, signaling to them to sit as well. When he finished the prayer, he said, "The imam is appointed only to be followed. When he says the takbir, say the takbir. When he bows, bow. When he says, 'Allah hears whoever praises Him,' say, 'Our Lord, to You belongs all praise.' When he prostrates, prostrate. And if he prays sitting, then all of you pray sitting."

Ahmad 12656

Sahih

حدثنا عبد الرزاق حدثنا معمر عن الزهري

عن أنس قال

سقط النبي ﷺ من فرس فجحش شقه الأيمن فدخلوا عليه فصلى بهم قاعدا وأشار إليهم أن اقعدوا فلما سلم قال إنما جعل الإمام ليؤتم به فإذا كبر فكبروا وإذا ركع فاركعوا وإذا قال سمع الله لمن حمده فقولوا ربنا ولك الحمد وإذا سجد فاسجدوا وإن صلى جالسا فصلوا جلوسا أجمعون

أحمد 12656صحيح
Contents
Reference
Commentary
Ayat
Collection
Musnad Ahmad
Book
Anas bin Malik
Numbering
Darussalam 12656
Ahmad 12656