Chapter: Observing Saum (fast) on the day of Ashura.

The Prophet (ﷺ) said, "Whoever wishes may fast on the day of 'Ashura'."

Allah's Messenger (ﷺ) ordered (the Muslims) to fast on the day of 'Ashura', and when fasting in the month of Ramadan was prescribed, it became optional for one to fast on that day ('Ashura') or not.

Quraish used to fast on the day of 'Ashura' in the Pre-Islamic period, and Allah's Messenger (ﷺ) too, used to fast on that day. When he came to Medina, he fasted on that day and ordered others to fast, too. Later when the fasting of the month of Ramadan was prescribed, he gave up fasting on the day of 'Ashura' and it became optional for one to fast on it or not.

That he heard Muawiya bin Abi Sufyan on the day of 'Ashura' during the year he performed the Hajj, saying on the pulpit, "O the people of Medina! Where are your Religious Scholars? I heard Allah's Apostle saying, 'This is the day of 'Ashura'. Allah has not enjoined its fasting on you but I am fasting it. You have the choice either to fast or not to fast (on this day).' "

The Prophet (ﷺ) came to Medina and saw the Jews fasting on the day of Ashura. He asked them about that. They replied, "This is a good day, the day on which Allah rescued Bani Israel from their enemy. So, Moses fasted this day." The Prophet (ﷺ) said, "We have more claim over Moses than you." So, the Prophet fasted on that day and ordered (the Muslims) to fast (on that day).

The day of 'Ashura' was considered as `Id day by the Jews. So the Prophet (ﷺ) ordered, "I recommend you (Muslims) to fast on this day."

I never saw the Prophet (ﷺ) seeking to fast on a day more (preferable to him) than this day, the day of 'Ashura', or this month, i.e. the month of Ramadan.

The Prophet (ﷺ) ordered a man from the tribe of Bani Aslam to announce amongst the people that whoever had eaten should fast the rest of the day, and whoever had not eaten should continue his fast, as that day was the day of 'Ashura'.