Musnad Ahmad 30:716

Muhammad ibn Bakr narrated to us, Ibn Jurayj narrated to us, ‘Ata’ informed me that he heard Abu Hurayrah—while he was informing them—say: "And in every prayer there is recitation. So whatever the Messenger of Allah (peace and blessings of Allah be upon him) made us hear, we have made you hear, and whatever he kept hidden from us, we have kept hidden from you."