(25) باب التَّرْغِيبِ فِي قِيَامِ رَمَضَانَ وَهُوَ التَّرَاوِيحُ
Abu Huraira reported Allah's Messenger (ﷺ) as saying:
He who observed the fasts of Ramadan with faith and seeking reward (from Allah), all his previous sins would be forgiven, and he who observed prayer on Lailat-ul- Qadr with faith and seeking reward (from Allah), all his previous sins would be forgiven.
Reference: Sahih Muslim 760 a
In-book reference: Book 6, Hadith 209
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1664