It is held to be the most sacred of all the months, excluding Ramadan. Muslims fast during these days. The tenth day of Muharram is called Yaumu-l ‘Ashurah, and the ninth as Tasuaa.
Many Muslims fast during this days, as gratefulness towards Allah, because of the many graces from Allah the Almighty were bestowed on the Islamic history like Musa the prophet (Alaihissalaaam ) and his people obtained a victory over the Egyptian Pharoas on the 10th day of Muharram; according to them Prophet Muhammed Peace and grace of Allah be upon him asked Muslims to to fast on this day, and also a day extra either before or after, so that they are not similar to Jews who used to fast for one day due to the same reason.
The Prophet (peace and blessings of Allah be upon him) said: “The year is twelve months of which four are sacred, the three consecutive months of Dhu’l-Qa’dah, Dhu’l-Hijjah and Muharram, and Rajab Mudar which comes between Jumaada and Sha’baan.” (Reported by al-Bukhari, 2958).