Abu Qatada al - Ansari narrated that Muhammad was asked about fasting on the day of Arafah, whereupon he said: It expiates the sins of the preceding year and the coming year. Also about fasting on the Ashura (10 Muharram) he said: It expiates the sins of the preceding year.
benefit of fasting on the day of arafah
expiates the sins of the preceding year and the coming year.