Musnad Ahmad 27:584

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from al-Hakam, who said: I saw Tawus when he would begin the prayer, he would raise his hands, and when he would bow, and when he would raise his head from bowing. Then a man from his companions narrated to me that he (Tawus) narrates it from Ibn Umar, from the Prophet, may Allah bless him and grant him peace.