Hajb bin 'Umar حاجب بن عمر · Fasting (Kitab Al-Siyam)

When the Prophet (ﷺ) on the day of 'Ashurah and commanded us to fast on it, they (i.e. Companions) said: Messenger of Allah, this is a day which is considered great by Jews and Christians ? The Messenger of Allah (ﷺ) said: When the next year comes, we shall fast on the 9th of Muharram. But the next year the Messenger of Allah (ﷺ) breathed his last.