Prophet Muhammad was very concerned about fasting on the day of Ashura. The day of Ashura literally means the 10th, from the tenth day of Muharram.
And the fasting on this day was made obligatory even before Ramadan; it was made obligatory in the first year after the hijrah, and everybody had to fast the first year. Then Allah revealed Ramadan, so Ramadan became obligatory, and the next year, Muharram became recommended and not obligatory.
So, the first year of Islam, it was obligatory on all Muslims to fast on the 10th of Muharram, and then in the second year it went down from being obligatory to being recommended and strongly encouraged.
The Prophet said that it serves as a forgiveness for the sins of the previous year.
On this day of 10th of Muharram our Prophet told us that Moses was saved from Pharaoh, and that Noah’s ship landed on Mount Judy, that on these days many incidents happen in the past, that served as a day of celebration and rejoicing.
When the Prophet found out that the Jews were fasting on the 10th of Muharram as well, even though the blessings of the tenth were predating the knowledge of the Prophet about the Jews.
When he found out that they were fasting because on this day, they said, “Moses was saved and Pharaoh was drowned. So we take it as a day of celebration.”
The Prophet Muhammad said:
We have more right to Moses than you do.
In other words, we are the true followers of Moses and from that year onwards, he also encouraged everybody to fast on the 10th. He also said:
If I live one more year, I shall fast on the 9th and the 10th.
The scholars say, ‘to make our ritual different from the ritual of other religions and nations’.
Therefore, ideally it is to fast the ninth and the tenth even though our Prophet never did it because as he said in the hadith but he passed away the very year that he said it, so he never actually lived to the next year but he said:
If Allah allows me to live another year, I shall fast the 9th and the 10th of Muharram.
So, those who are able to fast the ninth and the tenth or the tenth and the 11th, it’s better, but if they cannot fast two days, then at least on the 10th they should definitely fast on that day and it is a day that insha Allah if you do it properly and sincerely the minor sins of the previous year are forgiven.
Martyrdom of Hussein
And no doubt, this day also is a day in which a historical tragedy occurred and that is the massacre of Hussein, the tragedy of Karbala. But that tragedy does not have anything to do with the sanctity of this day; it was a coincidence that it happened on that day.
And the fact of the matter is that the death of Hussein is a historical tragedy, but the blessings of the 10th of Muharram and the fasting of the 10th of Muharram is separate to the historical tragedy that occurred coincidentally on the 10th of Muharram in a later year of the Hijrah.
Unfortunately, people have taken this Massacre to imply and to give meaning to Muharram. But, Muharram was blessed and sacred before the massacre and the massacre has nothing to do with the sanctity of the month and the fasting of the month. Ashura was a day that was holy before Hussein was martyred on that day.
Therefore, we as Muslims, we take the 10th of Muharram not as a day of mourning but as a day of worship of Allah Almighty, where we are conscious of Allah even more and we come close to Allah through the action of fasting.
https://www.youtube.com/watch?v=dVVrMfDXzJE