Narrated Abu Huraira: The Prophet (ﷺ) said, “Whoever established prayers on the night of Qadr out of sincere faith and hoping for a reward from Allah, then all his previous sins will be forgiven; and whoever fasts in the month of Ramadan out of sincere faith, and hoping for a reward from Allah, then all his previous sins will be forgiven.” [Sahih al-Bukhari 1901].

—

عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ “‏ مَنْ قَامَ لَيْلَةَ الْقَدْرِ إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ، وَمَنْ صَامَ رَمَضَانَ إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ ‏”‏‏.(رواه البخاري 1901