Praise be to Allah the Lord of the Worlds.
The day of Ashura is the 10th of the month of Muharram, the day on which Almighty Allah rescued Prophet Moses (PBUH) and his people from the Pharaoh and his soldiers. Therefore, Moses (PBUH) fasted on that day as show of gratitude to Allah the Almighty. Moreover, Prophet Mohammad (PBUH) fasted on that day as well and commanded us to do so. Ibn Abbas (May Allah Be Pleased with them): The Prophet (PBUH) 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 (PBUH) 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)." [Al-Bukhari].
This Hadith indicates that Prophet Mohammad and Muslims have more claim on Mousa and other Prophets and Messengers than the Jews do. This is because they believe in all of them and make no distinction between them. This is in addition to loving, glorifying and respecting them and supporting their religion, Islam.
Prophet Mohammad (PBUH) has legislated-to the Muslim nation- fasting on the day of Ashura and urged them to do so. Ibn `Abbas (May Allah Be Pleased with them): "I never saw the Prophet (PBUH) 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." [Agreed upon]. He (PBUH) also said: "Fasting on the day of Arafah is an expiation for the preceding year and the following year. Fasting on the day of Ashura is an expiation for the preceding year."[An-Nissae']. In order for a person to receive the full reward from Almighty Allah, it is better that he/she fasts the 9th, 10th, and the 11th of Muharam, as stated by a group of scholars such as Ash-Shafii` and others. If that wasn't possible, then he/she can fast the day of Ashura with the day that comes before or after it. However, if he/she fasted only on the day of Ashura, then it is permissible. Al-Imam An-Nawawi (May Allah have mercy on him) stated: "The day of Ashura is the 10th of Muharam, and it is likable for a person to fast Tasua "(The ninth of Muharam) with it." [Rawdat At-Talibeen].
In conclusion, in terms of reward and desirability, there are three ranks (From lowest to highest) for fasting on the day Ashura: 1- Fasting the day of Ashura alone (10th of Muharam). 2- Fasting the 9th and 10th. 3- Fasting the 9th, the 10th and the 11th. And Allah The Almighty Knows Best.
