Sunan Abi Dawud, Hadith 5052

Narrated Buraydah ibn al-Hasib: The Prophet said: If anyone says in the morning or in the evening: "O Allah! Thou art my Lord; there is no god but Thee, Thou hast created me, and I am Thy servant and hold to Thy covenant and promise as much as I can; I seek refuge in Thee from the evil of what I have done: I acknowledge Thy favour to me, and I acknowledge my sin; pardon me, for none but Thee pardons sins, and dies during the daytime or during the night." he will go to Paradise.

حَدَّثَنَا أَحْمَدُ بْنُ يُونُسَ، حَدَّثَنَا زُهَيْرٌ، حَدَّثَنَا الْوَلِيدُ بْنُ ثَعْلَبَةَ الطَّائِيُّ، عَنِ ابْنِ بُرَيْدَةَ، عَنْ أَبِيهِ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ مَنْ قَالَ حِينَ يُصْبِحُ أَوْ حِينَ يُمْسِي اللَّهُمَّ أَنْتَ رَبِّي لاَ إِلَهَ إِلاَّ أَنْتَ خَلَقْتَنِي وَأَنَا عَبْدُكَ وَأَنَا عَلَى عَهْدِكَ وَوَعْدِكَ مَا اسْتَطَعْتُ أَعُوذُ بِكَ مِنْ شَرِّ مَا صَنَعْتُ أَبُوءُ بِنِعْمَتِكَ وَأَبُوءُ بِذَنْبِي فَاغْفِرْ لِي إِنَّهُ لاَ يَغْفِرُ الذُّنُوبَ إِلاَّ أَنْتَ ‏.‏ فَمَاتَ مِنْ يَوْمِهِ أَوْ مِنْ لَيْلَتِهِ دَخَلَ الْجَنَّةَ ‏" ‏ ‏.‏

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also referenced under: Hadith 5070 (DarusSalam)