Prayer
مَنْ قَامَ رَمَضَانَ إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ
Translation
Whoever stands (in prayer) during Ramadan with faith and seeking reward, his past sins will be forgiven.
Narrator
Abu Hurairah
Source
Sahih Bukhari
Bukhari 2009

