Jami` at-Tirmidhi, Book 48, Hadith 28 (In-Book) ⓘ

Abu Sa`eed (ra) narrated that : the Prophet said: “Whoever says, when he goes to his bed: ‘I seek forgiveness from Allah, [the Magnificent] the One whom there is none worthy of worship except for Him, the Living, the Sustainer, and I repent to Him (Astaghfirullāha [al-`Aẓim] alladhi lā ilāha illā huw, al-Ḥayyul-Qayyūm, wa atūbu ilaihi)’ three times, Allah shall forgive him his sins if they were like the foam of the sea, even if they were the number of leaves of the trees, even if they were the number of sand particles of `Alij, even if they were the number of the days of the world.”

حَدَّثَنَا صَالِحُ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا أَبُو مُعَاوِيَةَ، عَنِ الْوَصَّافِيِّ، عَنْ عَطِيَّةَ، عَنْ أَبِي سَعِيدٍ، رضى الله عنه عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ مَنْ قَالَ حِينَ يَأْوِي إِلَى فِرَاشِهِ أَسْتَغْفِرُ اللَّهَ الْعَظِيمَ الَّذِي لاَ إِلَهَ إِلاَّ هُوَ الْحَىَّ الْقَيُّومَ وَأَتُوبُ إِلَيْهِ ‏.‏ ثَلاَثَ مَرَّاتٍ غَفَرَ اللَّهُ ذُنُوبَهُ وَإِنْ كَانَتْ مِثْلَ زَبَدِ الْبَحْرِ وَإِنْ كَانَتْ عَدَدَ وَرَقِ الشَّجَرِ وَإِنْ كَانَتْ عَدَدَ رَمْلِ عَالِجٍ وَإِنْ كَانَتْ عَدَدَ أَيَّامِ الدُّنْيَا ‏" ‏ ‏.‏ قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ غَرِيبٌ لاَ نَعْرِفُهُ إِلاَّ مِنْ هَذَا الْوَجْهِ مِنْ حَدِيثِ الْوَصَّافِيِّ عُبَيْدِ اللَّهِ بْنِ الْوَلِيدِ ‏.‏