Anas bin Malik narrated:
Allah's Messenger fell from a horse and got injured, so he led Salat sitting and we also offered Salat sitting. When he completed the Salat he said: The Imam is appointed to be followed; when he says the Takbir then say the Takbir, when he bows, then bow, and when he raises his head, then raise your heads. When he says: Sami' Allahu liman hamidah (Allah listens to those who praise him) then say: Rabbana wa lakal-hamd. (O our Lord! And all praise is Yours.) and when he prostrates, then prostrate, and when he performs Salat sitting, then pray sitting altogether.'