Musnad Abu Ya'la al-Mawsili 113:15

Mukhlad ibn Abi Zumayl narrated to me, [saying]: Ubayd Allah ibn Amr al-Ruqqi narrated to us, from Ayyub, from Abu Qilabah, from Anas, that the Messenger of Allah (may Allah bless him and grant him peace) prayed with his companions. When he finished his prayer, he turned his face toward them and said: "Do you recite in your prayer behind the Imam while the Imam is reciting?" They remained silent. He said it three times. Then a speaker said, or speakers said: "We do indeed do that." He said: "Do not do so. Let one of you recite the Opening of the Book (al-Fatihah) to himself."