Musannaf Ibn Abi Shayba 3:117

Ibn ‘Uyaynah narrated to us, from al-Zuhri, who said: Ali ibn al-Husayn informed me, saying: It was the prayer of the Messenger of Allah (may Allah bless him and grant him peace). And it was mentioned to him that Abu Hurayrah used to say the takbir (Allahu Akbar) in every lowering and rising.