O Allah, forgive my past and future sins, and my secret and open sins
Authentic hadithعن علي بن أبي طالب رضي الله عنه قال: كان رسول الله صلى الله عليه وسلم إذا قام إلى الصلاة يكون من آخر ما يقول بين التشهد والتسليم: «اللهم اغفر لي ما قَدَّمتُ وما أخَّرْتُ، وما أسررتُ وما أعلنتُ، وما أسْرَفتُ، وما أنت أعلم به مني، أنت المُقَدِّم، وأنت المؤخر، لا إله إلا أنت».
‘Ali ibn Abi Tālib (may Allah be pleased with him) reported that the Messenger of Allah (may Allah’s peace and blessings be upon him) used to say at the end of prayer, between the Tashahhud and Taslīm: "O Allah, forgive my past and future sins, my secret and open sins, my transgression, and that of which You have better knowledge than I. Indeed, You are the One Who puts forward, and You are the One Who puts back. There is no god but You."
Explanation
The Prophet (may Allah's peace and blessings be upon him) used to say at the end of prayer, between the Tashahhud and Taslīm: "O Allah, Forgive my past and future sins, my secret and open sins, my transgression." He went to great lengths in asking his Lord for forgiveness by mentioning various types of sins. "And that of which You have better knowledge than I", meaning: my sins whose number and gravity are unknown to me. "Indeed, You are the One Who puts forward", meaning: you bring some slaves close to You by enabling them to obey and worship You. "And You are the One Who puts back", meaning: You make some of them lag behind through failure to act in a way pleasing to You. Or You put whomever You will at the ranks of perfection and keep whomever You will away from high ranks and deep into the lowest ones. "There is no god but You." There is no one worthy of being worshiped except You.
Source · Narrated by Muslim
From the Hadith Encyclopedia (hadeethenc.com).