The Prophet (“ﷺ”) said “The best of fasts after the month of Ramadan is in the Month of Allah, which you call Muharram” (Sahih Muslim)

The 10th of Muharram is the Day of Ashura. Fasting on the Day of Ashura has several benefits, one of which is that Allah (SWT) will atone for your sins from the previous year!
Our beloved Prophet (“ﷺ”) prayed to Allah to pardon all those who fast on the Day of Ashura for the sins they committed the year prior, according to a Hadith related by Imam Muslims.
In addition to the days of Ramadan, The Prophet (“ﷺ”) emphasized the Ashura Day fast over other days, according to Ibn Abbas (RA) “I have never seen Rasulullah (“ﷺ”) so eager to fast like he is for Ashura and prioritizing it, besides Ramadan.” (Sahih Muslim)

However, as the Prophet (“ﷺ”) noted, fasting on the Day of Ashura is a voluntary deed (Sunnah) and not an obligation (Wajib):
The Prophet (SWT) “Fast if you wish and those who do not, are not obliged to do so.” (Sahih Al-Bukhari)
The Ashura fast is observed on the tenth day of Muharram. Muslim fasting on the ninth and eleventh of Muharram, the days before and following Ashura, is also encouraged.

According to a hadith, the Prophet (“ﷺ”) said: “Fast on the day before and the day after Ashura”. (Musnad Ahmad)

According to Imam ibn Al-Qayyim, there are three levels of fasting on Ashura, with the first level being “the best” and “most complete,” and the other two levels following suit:
• Fasting for three days in a row (9, 10, and 11 Muharram).
• Only fasting on Muharram 9, 10, and 11.
• Only observe the fast on Muharram 10th.

There is, however, no commitment. You are free to carry out whatever is most practicable and convenient for you.

Do not ignore this day saying it’s just a Sunnah, it has more benefits in it

Oh Allah, make it an easy one for us all, accept our fasting and all our Dua, and make these days a beneficial one to us all