Musnad Ahmad 30:3193

Isma'il and Ibn Ja'far narrated to us, they said: Ibn Jurayj narrated to us, from 'Ata'. Ibn Ja'far said in his hadith: 'Ata' narrated to me that he heard Abu Hurayrah saying: "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."