Musnad Abu Ya'la al-Mawsili 160:220

Sufyan ibn Waki' narrated to us, my father narrated to us, Yahya ibn 'Umayr al-Madini narrated to us, he said: I heard Sa'id al-Maqburi saying: Abu Hurayrah led us in prayer, and he would say the takbir whenever he raised [his head] and prostrated. When he finished, he said: "This is how the Messenger of Allah (may Allah bless him and grant him peace) used to lead us in prayer."