Sahih Muslim Book 4, Hadith Number 819.

Chapter : The reciting of Tasmi’ (Allah listens to him who praises Him) Tahmid (O our Lord, for Thee is the praise), and Timin (Amin).

Anas b. Malik reported: The Messenger of Allah (may peace be upon him) fell down from a horse and his right side was grazed, and the rest of the Hadith is the same with the addition of these words: “When he (the Imam) says prayer standing, you should also do so.”