NASAI-KUBRA 2523:
from al-Nabī ﷺ —
"Whoever fasts during Ramadan" and according to the Hadith of Qutaibah, the Prophet said: "Whoever spends the nights of Ramadan in prayer (Qiyam) out of faith and in the hope of reward, he will be forgiven his previous sins, and whoever spends the night of Lailat Al-Qadr in prayer out of faith and in the hope of reward, he will be forgiven his previous sins." ' (Using translation from Nasāʾī 2202)
الكبرى للنسائي ٢٥٢٣:
عن النبي ﷺ —
عَنِ النَّبِيِّ ﷺ قَالَ مَنْ قَامَ رَمَضَانَ فِي حَدِيثِ قُتَيْبَةَ أَنَّ النَّبِيَّ ﷺ قال «مَنْ قَامَ شهر رَمَضَانَ» إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ «فِي حَدِيثِ قُتَيْبَةَ» وَمَا تَأَخَّرَ وَمَنْ قَامَ لَيْلَةَ الْقَدْرِ إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ «وفِي حَدِيثِ قُتَيْبَةَ» وَمَا تَأَخَّرَ
hadithunlocked.com