The day of Ashura in Islam

Muharram is the first month of the Islamic lunar calendar. The tenth day of this month has a special name “Ashura”. What does one get for fasting it? The Prophet Muhammad (peace and blessings be upon him) informed us, “Fasting the day of Ashura is an expiation for (sins committed in) the past year.” (Narrated by Muslim)
We all know that Muharram is one of the sacred months, which Allah, the Sublime, about which he said His Holy Book, “Indeed, the number of months with Allah is twelve [lunar] months in the register of Allah [from] the day He created the heavens and the earth; of these, four are sacred. That is the correct religion, so do not wrong yourselves during them.” (Sura At Tawbah, ayah 36).
The Arabs used to consider these months sacred during the time of Jahiliyyah, except for a group called AlBasl who held eight months of the year to be sacred as being of extra significance in religion. Muharram is an honourable month of the Islamic year and it is called so (i.e. forbidden) because fighting was then forbidden and Almighty Allah forbade us from committing injustice in them as a kind honour to it, although injustice is extremely forbidden at all times. Therefore, we must adhere to the commandments of Almighty Allah and His Messenger (peace and blessings be upon him) and not commit sins in this month because of its sanctity and sacredness.