Musnad Ahmad 5:396

Rawh narrated to us, Ibn Jurayj narrated to us, Musa ibn Uqbah informed me, from Abdullah ibn al-Fadl, from Abd al-Rahman al-A'raj, from Ubayd Allah ibn Abi Rafi', from Ali ibn Abi Talib, that the Prophet, peace and blessings of Allah be upon him, used to say when he bowed: "O Allah, to You I have bowed, and in You I have believed, and to You I have submitted. You are my Lord. My hearing, my sight, my marrow, my bone, and my sinew have humbled themselves, as well as what my feet have carried, to Allah, Lord of the worlds."