Musnad Ahmad 30:2207

Muhammad ibn Ja'far narrated to us, he said: Sa'id—meaning Ibn Abi 'Arubah—narrated to us, from Abu Muhammad—I think he is Habib ibn al-Shahid—from 'Ata' ibn Abi Rabah, from Abu Hurairah, who said: "In every prayer, recitation is performed. So, whatever the Messenger of Allah (ﷺ) made us hear, we have made you hear, and whatever he kept hidden from us, we have kept hidden from you."