It wasnarrated from Abu Qatadah that the Messenger of Allah (ﷺ)said:
"Fasting on the Day of 'Arafah, I hope from Allah, expiates forthe sins of the year before and the year after." (FR)
English reference (FR): Vol. 1, Book 7, Hadith 1730 (FR)
Arabic reference (FR): Book 7, Hadith 1802 (FR)