Musannaf Ibn Abi Shayba 3:22

Abu Bakr narrated to us, he said: Suwayd ibn ‘Amr al-Kalbi narrated to us, he said: ‘Abd al-‘Aziz ibn Abi Salamah narrated to us, he said: al-Majishun informed me, from my paternal uncle, from al-A‘raj, from ‘Ubayd Allah ibn Abi Rafi‘, from ‘Ali, who said: When the Prophet, peace and blessings of Allah be upon him, would begin the prayer, he would say the takbir, then he would say: "I have turned my face toward Him who created the heavens and the earth, inclining toward truth, and I am not of the polytheists. Indeed, my prayer, my rites of 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 the first of the Muslims. O Allah, You are the Sovereign; 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, for 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 except You. I am here at Your service and obedient to You, and all good is in Your hands. I am by You and toward You. Blessed are You and Exalted. I seek Your forgiveness and I repent to You."