Bayhaqi 2344 — The opening supplication after the takbir

It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) that, indeed, when the Messenger of Allah (peace and blessings be upon him) began an obligatory prayer, he would recite: 'Wajjahtu wajhiya lilladhi fatara al-samawati wa al-arda hanifan musliman wa ma ana min al-mushrikin, inna salati wa nusuki wa mahyaya wa mamati lillahi rabbi al-'alamin, la sharika lahu wa bidhalika umirtu wa ana min al-muslimin. Allahumma anta al-maliku la ilaha illa ant, subhanaka wa bihamdik, anta rabbi wa ana 'abduk, zalamtu nafsi wa'taraftu bidhanbi, faghfir li dhunubi jami'an, la yaghfiru al-dhunuba illa ant, wahdini li-ahsani al-akhlaqi la yahdi li-ahsaniha illa ant, wasrif 'anni sayyi'aha la yasrifu sayyi'aha illa ant, labbayka wa sa'dayk, wa al-khayru kulluhu biyadayk, wa al-mahdiyyu man hadayt, ana bika wa ilayk, tabarakta wa ta'alayt, astaghfiruka wa atubu ilayk' (I have turned my face towards the One who is the Creator of the heavens and the earth. I submit to Him, and I am not of the polytheists. Indeed, my prayer, my sacrifice, my living and my dying are for Allah Almighty, who is the Lord of all the worlds; He has no partner, with this I have been commanded, and I am of the Muslims. O Allah, You are the King; there is no true god except You. You are free of all imperfection and all praise is Yours. You are my Lord and I am Your servant. I have wronged myself and I admit my sin, so forgive me all my sins; there is none who forgives sins except You. Guide me to good manners; there is none who guides to good manners except You, and keep bad manners away from me; there is none who keeps bad manners away except You. Here I am at Your court; all good things are in Your hands, and the one on the straight path is the one whom You have guided. I am with You and I make my entreaty to You alone. You are Blessed and Exalted. I seek Your forgiveness and I turn to You alone in repentance). When he (peace and blessings be upon him) bowed, he would say: 'Allahumma laka raka'tu wa bika amantu wa laka aslamtu, anta rabbi, khasha'a laka sam'i wa basari wa mukhkhi wa 'izami wa ma istaqallat bihi qadami lillahi rabbi al-'alamin' (O Allah, for You I have bowed, in You I have believed and to You I have submitted. You are my Lord. My ears, my eyes, my brain, my bones and that upon which my feet stand, O Allah, all are humbled before You alone; You are the Lord of all the worlds).
And when he raised his head from bowing in the obligatory prayer, he would say: 'Allahumma rabbana wa laka al-hamdu mil'a al-samawati wa mil'a al-ardi wa mil'a ma shi'ta min shay'in ba'd' (O our Lord, praise belongs to You alone, so much that all the heavens and the earth are filled, and everything You will after them is filled).