The Book of Prayer - Travellers
6/25. Chapter:
Encouragement to pray qiyam during Ramadan, which is Tarawih
Sahih Muslim
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنِ ابْنِ شِهَابٍ، عَنْ حُمَيْدِ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " مَنْ قَامَ رَمَضَانَ إِيمَانًا وَاحْتِسَابًا غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ " .
Abu Huraira reported Allah's Messenger (ﷺ) as saying: He who observed prayer at night during Ramadan, because of faith and seeking his reward from Allah, his previous sins would be forgiven.
Reference : Sahih Muslim 759aIn-book reference : Book 6, Hadith 207USC-MSA web (English) reference : Book 4, Hadith 1662