Abu Hurairah (May Allah be pleased with him) reported:
The Prophet (ﷺ) said, "He who observes fasting during the month of Ramadan with Faith while seeking its reward from Allah, will have his past sins forgiven."[Al-Bukhari and Muslim]. (TR)
App reference (TR): Book 9, Hadith 229 (TR)
Arabic/English book reference (TR): Book 9, Hadith 1219 (TR)