10th of Muharram (the day of Ashura) is observed as an important day by Muslims . Based on the Hadith of Prophet Muhammad (saws), Muslims celebrate Ashura as the day when Prophet Moses (Moosa) fasted on that day because Allah saved the Israelites from their enemy in Egypt. One of the many Ahadith (sayings of Prophet Muhammad) that attests to that is in Bukhari that states:
Narrated by al-Bukhaari (1865) from Ibn ‘Abbaas, who said: The Prophet (saws) came to Madinah and saw the Jews fasting on the day of Ashoora. He said, “What is this?” They said, “This is a good day, this is the day when Allah saved the Children of Israel from their enemy and Moosa fasted on this day.” He (the Prophet Muhammad) said, “We are closer to Moosa than you.”
So he (the Prophet Muhammad) fasted on this day and told the people to fast. There are many other versions of this Hadith in the books of “Muslim” and “Bukhari”. According to a version narrated by Muslim, This is a great day when Allah saved Moosa (Moses) and his people and drowned Pharaoh and his people.” Sunni Muslims celebrate Ashura by fasting on that day. Usually, Sunni Muslims are recommended to fast on the 9th and 10th of Muharram.
Other Ahadith on the subject are the following:
The prophet observed the fast on Ashuraa (the 10th of Muharram), and ordered (Muslims) to fast on that day. (Agreed upon Hadith i.e. Bukhari & Muslim).
Narrated by Abi Katada: The prophet was asked about fasting on ‘Ashuraa’ (the 10th of Muharram), he said: “it expiates the previous year (for sins).” (Sahih Muslim)
It was proven from the Prophet (peace and blessings of Allaah be upon him) that the best fasting after Ramadaan is fasting in the month of Muharram. It was narrated that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “The best fasting after Ramadaan is the month of Muharram, and the best prayer after the obligatory prayer is prayer at night.” Narrated by Muslim, 1163.
As 10th of Muharram for the year 1435 Hijri will fall on November 14th, 2013, that day and the day before or after will be the two days Muslims should be looking to fast.