´Abu Sa`eed (ra) narrated that :` the Prophet (ﷺ) 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.”
Hadith Referenceسنن ترمذي / كتاب الدعوات عن رسول الله صلى الله عليه وسلم / 3397
Hadith Gradingالألبانی:ضعيف الكلم الطيب (39) ، التعليق الرغيب (1 / 211) // ضعيف الجامع الصغير (5728) // | زبیر علی زئی:(3397) إسناده ضعيف, عطية العوفي : ضعيف (تقدم:477)