Hadith
حَدَّثَنَا الْحَسَنُ بْنُ عَلِيٍّ، وَمُحَمَّدُ بْنُ الْمُتَوَكِّلِ، قَالاَ حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، - قَالَ الْحَسَنُ فِي حَدِيثِهِ وَمَالِكُ بْنُ أَنَسٍ - عَنِ الزُّهْرِيِّ، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُرَغِّبُ فِي قِيَامِ رَمَضَانَ مِنْ غَيْرِ أَنْ يَأْمُرَهُمْ بِعَزِيمَةٍ ثُمَّ يَقُولُ " مَنْ قَامَ رَمَضَانَ إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ " . فَتُوُفِّيَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَالأَمْرُ عَلَى ذَلِكَ ثُمَّ كَانَ الأَمْرُ عَلَى ذَلِكَ فِي خِلاَفَةِ أَبِي بَكْرٍ - رضى الله عنه - وَصَدْرًا مِنْ خِلاَفَةِ عُمَرَ رضى الله عنه . قَالَ أَبُو دَاوُدَ وَكَذَا رَوَاهُ عُقَيْلٌ وَيُونُسُ وَأَبُو أُوَيْسٍ " مَنْ قَامَ رَمَضَانَ " . وَرَوَى عُقَيْلٌ " مَنْ صَامَ رَمَضَانَ وَقَامَهُ " .
Narrated Abu Hurairah:The Messenger of Allah (ﷺ) used to commend prayer at night during Ramadan, but did not command it as duty. He would say: If anyone prays during the night in Ramadan because of faith and seeking his reward from Allah, his previous sins will be forgiven for him. When the Messenger of Allah (ﷺ) died, this was the practice, and it continued thus during Abu Bakr's caliphate and early part of 'Umar's. Abu Dawud said: This tradition has been transmitted by 'Uqail, Yunus, and Abu Uwais in like manner. The version of 'Uqail goes: He who fasts during Ramadan and prays during the night
Sahih · Al-Albani
Sunan Abi Dawud 1371 ·Book 6, Hadith 1·Also available on sunnah.com·