Fasting the day of 'Arafah:
Abu Qatādah Al-Ansāri, radhiaAllahu 'anhu, narrated:
The Messenger of Allah ﷺ was asked about the fast of the day of Arafah (the 9th of Dhul-Hijjah). He replied: "It expiates [the sins of] the preceding year and the coming year,” and he was asked about fasting on the day of 'Āshūrā (the 10th of Muharram). He replied: "It expiates [the sins of] the preceding year,” and he was asked about fasting on Monday, and he replied: "That is the day on which I was born, and on which I was sent (as a Prophet) and on which [the Qurān] was revealed to me."
- Reported by Muslim in his Sahīh
Abu Qatādah Al-Ansāri, radhiaAllahu 'anhu, narrated:
The Messenger of Allah ﷺ was asked about the fast of the day of Arafah (the 9th of Dhul-Hijjah). He replied: "It expiates [the sins of] the preceding year and the coming year,” and he was asked about fasting on the day of 'Āshūrā (the 10th of Muharram). He replied: "It expiates [the sins of] the preceding year,” and he was asked about fasting on Monday, and he replied: "That is the day on which I was born, and on which I was sent (as a Prophet) and on which [the Qurān] was revealed to me."
- Reported by Muslim in his Sahīh