عَنْ عَبْدِ الرَّحْمَنِ بْنِ عَوْفٍ رَضِيَ اللَّهُ عَنْهُ عَنْ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ: ((إِنَّ اللَّهَ عَزَّ وَجَلَّ فَرَضَ صِيَامَ رَمَضَانَ وَسَنَنْتُ قِيَامَهُ، فَمَنْ صَامَهُ وَقَامَهُ احْتِسَابًا خَرَجَ مِنَ الذُّنُوبِ كَيَوْمِ وَلَدَتْهُ أُمُّهُ))
It is narrated from Sayyiduna Abdur Rahman bin Awf (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: Indeed, Allah Almighty has made the fasting of Ramadan obligatory, and I have made its night prayer a Sunnah. So whoever fasts during it and stands (in prayer) seeking reward, he will emerge from sins as the day his mother gave birth to him.