Musnad Ahmad 25:419

Yunus ibn Muhammad narrated to us, Abd al-Aziz—meaning al-Dabbagh—narrated to us, from Abdullah al-Danaj, Ikrimah, the freed slave of Ibn Abbas, narrated to us, saying: "I prayed behind Abu Hurairah, and he would say the takbir when he bowed and when he prostrated." He said: "I mentioned that to Ibn Abbas, and he said: 'May you have no mother! Is that not the Sunnah of the Messenger of Allah, may Allah bless him and grant him peace?'"