It wasnarrated that Qatadah bin Nu'man said:
"I heard the MessengerofAllah (ﷺ) say: 'Whoever fasts the Day of 'Arafah, his sins oftheprevious and following year will be forgiven.'" (FR)
English reference (FR): Vol. 1, Book 7, Hadith 1731 (FR)
Arabic reference (FR): Book 7, Hadith 1803 (FR)