Sahih Bukhari, Chapter: Characteristics of Prayer

'Imran bin Husain and I offered the prayer behind Ali bin Abi Talib. When 'Ali prostrated, he said the Takbir, when he raised his head, he said the Takbir and when he got up for the third Rak'a he said the Takbir. On completion of the prayer Imran took my hand and said, "This (i.e. 'Ali) made me remember the prayer of Muhammad" Or he said, "He led us in a prayer like that of Muhammad."