Sunan an-Nasa'i 5522

أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَزِيدُ، - وَهُوَ ابْنُ زُرَيْعٍ - قَالَ حَدَّثَنَا حُسَيْنٌ الْمُعَلِّمُ، عَنْ عَبْدِ اللَّهِ بْنِ بُرَيْدَةَ، عَنْ بُشَيْرِ بْنِ كَعْبٍ، عَنْ شَدَّادِ بْنِ أَوْسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ إِنَّ سَيِّدَ الاِسْتِغْفَارِ أَنْ يَقُولَ الْعَبْدُ اللَّهُمَّ أَنْتَ رَبِّي لاَ إِلَهَ إِلاَّ أَنْتَ خَلَقْتَنِي وَأَنَا عَبْدُكَ وَأَنَا عَلَى عَهْدِكَ وَوَعْدِكَ مَا اسْتَطَعْتُ أَعُوذُ بِكَ مِنْ شَرِّ مَا صَنَعْتُ أَبُوءُ لَكَ بِذَنْبِي وَأَبُوءُ لَكَ بِنِعْمَتِكَ عَلَىَّ فَاغْفِرْ لِي فَإِنَّهُ لاَ يَغْفِرُ الذُّنُوبَ إِلاَّ أَنْتَ فَإِنْ قَالَهَا حِينَ يُصْبِحُ مُوقِنًا بِهَا فَمَاتَ دَخَلَ الْجَنَّةَ وَإِنْ قَالَهَا حِينَ يُمْسِي مُوقِنًا بِهَا دَخَلَ الْجَنَّةَ ‏"‏ ‏.‏ خَالَفَهُ الْوَلِيدُ بْنُ ثَعْلَبَةَ ‏.‏

It was narrated from Shaddad bin Aws that :The Prophet [SAW] said: "The best of prayers for forgiveness is for a person to say: 'Allahumma, anta rabbi, la ilaha illa anta, khalaqtani wa ana 'abduka, wa ana 'ala 'ahdika wa wa'dika mastata'tu, a'udhu bika min sharri ma sana'tu, abuw'u laka bidhanbi, wa abuw'u laka bini'matika 'alayya faghfirli, fa innahu la yaghfirudh-dhunuba illa anta (O Allah, You are my Lord, there is no god but You. You have created me and I am Your slave and I am keeping my promise and covenant to You as much as I can. I seek refuge with You from the evil of what I do. I acknowledge Your blessing and I acknowledge my sin, so forgive me, for there is none who can forgive sin except You.)' If he says this in the morning, believing in it firmly, and dies on that day before evening comes, he will enter Paradise, and if he says it in the evening, believing firmly in it, and dies before morning comes, he will enter Paradise." Al-Walid bin Tha'labah contradicted him

Reference

Sunan an-Nasa'i 5522

In-book

Book 50, Hadith 95