Musnad Ahmad 614:1

'Abd al-Razzaq narrated to us, Sufyan narrated to us, from Khalid al-Hadhdha', from Abu Qilabah, from Muhammad ibn Abi 'A'ishah, from a man among the companions of the Prophet, may Allah bless him and grant him peace, who said: The Prophet, may Allah bless him and grant him peace, said: "Perhaps you recite while the Imam is reciting," [repeating it] twice or thrice. They said: "O Messenger of Allah, we indeed do that." He said: "Do not do so, except that one of you recites the Opening of the Book (Fatihat al-Kitab)."