Musnad Ahmad 5:167

Abu Sa’id narrated to us, ‘Abd al-‘Aziz ibn ‘Abd Allah al-Majishun narrated to us, ‘Abd Allah ibn al-Fadl and al-Majishun narrated to us, from al-A’raj, from ‘Ubayd Allah ibn Rafi’, from ‘Ali ibn Abi Talib, that the Messenger of Allah (may Allah bless him and grant him peace), when he said the takbir, would open [the prayer] and then say: "I have turned my face toward Him who created the heavens and the earth, inclining toward truth, a Muslim, and I am not of the polytheists. Indeed, my prayer, my sacrifice, my living, and my dying are for Allah, Lord of the worlds. No partner has He. And of this I have been commanded, and I am of the Muslims" — and Abu al-Nadr said: "And I am the first of the Muslims." "O Allah, there is no god but You. You are my Lord and I am Your servant. I have wronged my soul and I have confessed my sin, so forgive me all my sins; none forgives sins except You. Guide me to the best of characters, for none guides to the best of them except You. And turn away from me their evil, for none turns away their evil from me except You. Blessed are You and Exalted. I seek Your forgiveness and I repent to You." And when he bowed, he would say: "O Allah, to You I have bowed, in You I have believed, and to You I have submitted. My hearing, my sight, my marrow, my bones, and my nerves have humbled themselves before You." And when he raised his head from the bowing, he would say: "Allah hears those who praise Him. Our Lord, and to You be the praise, filling the heavens and the earth and what is between them, and filling whatever You will of anything thereafter." And when he prostrated, he would say: "O Allah, to You I have prostrated, in You I have believed, and to You I have submitted. My face has prostrated to the One who created it and fashioned it and perfected its form, and brought forth its hearing and its sight. So blessed is Allah, the best of creators." And when he finished the prayer with the taslim, he would say: "O Allah, forgive me what I have sent forth and what I have delayed, what I have concealed and what I have declared, what I have exceeded, and that which You know better than I. You are the Advancer and You are the Delayer. There is no god but You."