Sunan an-Nasa'i 2205
سنن النسائي#2205Sahihأَخْبَرَنَا عَلِيُّ بْنُ الْمُنْذِرِ، قَالَ حَدَّثَنَا ابْنُ فُضَيْلٍ، قَالَ حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، رضى الله عنه قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ صَامَ رَمَضَانَ إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ " .
It was narrated that Abu Hurairah said:"The Messenger of Allah said: 'Whoever fasts Ramadan out of faith and in the hope of reward, he will be forgiven his previous sins
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih Bukhari
In-book reference: 22:116