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].

وعن أبي هريرة رضي الله عنه عن النبي ﷺ قال: من صام رمضان إيمانًا واحتسابًا، غفر له ما تقدم من ذنبه " ((متفق عليه))