Abu Hurairah narrated that The Messenger of Allah (ﷺ) said:
"Whoever prays during the night in Ramadan out of sincere faith and seeking its reward from Allah, will have all of his previous sins forgiven." Agreed upon. (IT)
English reference (IT): Book 5, Hadith 717 (IT)
Arabic reference (IT): Book 5, Hadith 697 (IT)