Abu Hurairah (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) said, "He who observes optional prayer (Tarawih prayers) throughout Ramadan, out of sincerity of Faith and in the hope of earning reward will have his past sins pardoned."[Al- Bukhari and Muslim].
App reference: Book 9, Hadith 197
Arabic/English book reference: Book 9, Hadith 1187