Allah’s sacred month of Muharram is a blessed and important month. It is the first month of the Hijri calendar and is one of the four sacred months
The 10th day of month of Muharram is called Ashurah and fasting on that day and the day before or after is very valuable.
Let me provide you some ahadith about this day insha'Allah:
Abu Hurayrah (may Allah be pleased with him) said:
“The Messenger of Allah (peace and blessings of Allah be upon him) said: ‘The best of fasting after Ramadhan is fasting Allah’s month of Muharram.’ ”
(Muslim, 1982)
Ibn ‘Abbas (may Allah be pleased with him) said: “The Prophet (peace and blessings of Allah be upon him) came to Madinah and saw the Jews fasting on the day of ‘Ashura’. He said, ‘What is this?’ They said, ‘This is a righteous day, it is the day when Allah saved the Children of Israel from their enemies, so Musa fasted on this day.’ He said, ‘We have more right to Musa than you,’ so he fasted on that day and commanded [the Muslims] to fast on that day.”
(Bukhari, 1865)
Ibn 'Abbas (may Allah be pleased with them both) said:
“I never saw the Messenger of Allah (peace and blessings of Allah be upon him) so keen to fast any day and give it priority over any other than this day, the day of 'Ashura’, and this month, meaning Ramadhan.”
(Bukhari, 1867)
It is Mustahabb (Encouraged) to Fast Tasu'a’ with 'Ashura’
'Abdullah ibn 'Abbas (may Allah be pleased with them both) said: “When the Messenger of Allah (peace and blessings of Allah be upon him) fasted on 'Ashura’ and commanded the Muslims to fast as well, they said, 'O Messenger of Allah, it is a day that is venerated by the Jews and Christians.’ The Messenger of Allah (peace and blessings of Allah be upon him) said, 'If I live to see the next year, in sha Allah, we will fast on the ninth day too.’ But it so happened that the Messenger of Allah (peace and blessings of Allah be upon him) passed away before the next year came.”
(Muslim, 1916)
Some scholars recommend fasting on the 9th of Muharram as well to be on the safe side or to be different from the Jews and Christians.
So when is the day of Ashurah?
Day before Ashura
9th Muharram - August 7 th 2022
Ashura
10th Muharram - August 8 th 2022
Day After Ashura
11th Muharram - August 10 th 2022
Please keep in mind that it is not obligatory to fast on these days but very very valuable sunnah!
A'isha (Allah be pleased with her) reported that the Quraish used to fast on the day of 'Ashura in the pre-Islamic days and the Messenger ot Allaah (sallAllaahu alayhi wa sallam) also observed it. When he migrated to Medina, he himself observed this fast and commanded (others) to observe it. But when fasting during the month of Ramadan was made obligatory he said: He who wishes to observe this fast may do so, and he who wishes to abandon it may do so.
(Muslim 2499)