Sunan an-Nasa'i
Book 47: The Book Of Faith and its Signs
كتاب الإيمان وشرائعه
55 hadith in this book
Abu Hurairah narrated that: The Messenger of Allah (ﷺ) [SAW] said: "Whoever stands (in the voluntary night prayer of) Ramadan out of faith and in the hope of reward, his previous sins will be forgiven. And whoever spends the night of Lailat Al-Qadr in prayer out of faith and in the hope of reward, his previous sins will be forgiven."
حَدَّثَنَا أَبُو الْأَشْعَثِ قَالَ حَدَّثَنَا خَالِدٌ يَعْنِي ابْنَ الْحَارِثِ قَالَ حَدَّثَنَا هِشَامٌ عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ عَنْ أَبِي سَلَمَةَ بْنِ عَبْدِ الرَّحْمَنِ قَالَ حَدَّثَنِي أَبُو هُرَيْرَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ مَنْ قَامَ رَمَضَانَ إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ وَمَنْ قَامَ لَيْلَةَ الْقَدْرِ إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ
Hadith text, translations and grading are courtesy of Sunnah.com.