Maliks Muwatta Book 003, Hadith Number 046.

Section : Not Reciting behind the Imam when He Recites Aloud.

Yahya related to me from Malik from Ibn Shihab from Ibn Ukayma al-Laythi from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, finished a prayer in which he had recited aloud and asked, "Did any of you recite with me just now?" One man said, "Yes, I did, Messenger of Allah." The Messenger of Allah, may Allah bless him and grant him peace, said, "I was saying to myself, 'Why am I distracted from the Qur'an?' " When the people heard the Messenger of Allah, may Allah bless him and grant him peace, say that, they refrained from reciting with the Messenger of Allah, may Allah bless him and grant him peace, when he recited aloud.