Sahih Muslim Book 4, Hadith Number 825.

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

Jabir said: The Messenger of Allah (may peace be upon him) led the prayer and Abu Bakr was behind him. When the Messenger of Allah (may peace be upon him) recited the takbir, Abu Bakr also recited (it) in order to make it audible to us. And the rest of the Hadith is like one transmitted by Laith.