Musannaf Ibn Abi Shayba 3:1284

Ghundar narrated to us, from Shu'bah, from Abu Bishr, from Sa'id ibn Jubayr, from Ibn 'Umar, that he saw a man reciting aloud during the day. So he called him and said, "Indeed, the prayer of the day is not recited aloud in, so lower your recitation."