The Book of Fasting
22/39. Chapter:
The Reward of one who prays Qiyam in Ramadan and fasts the month out of faith and hope for reward
Sunan an-Nasai
أَخْبَرَنَا 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." '
Reference : Sunan an-Nasa'i 2205In-book reference : Book 22, Hadith 116English translation : Vol. 3, Book 22, Hadith 2207