

اَلسَلامُ عَلَيْكُم وَرَحْمَةُ اَللهِ وَبَرَكاتُهُ
﷽
Peace and blessings be upon you all.
In the Name of Allahﷻالله, the Most Beneficent, the Most Merciful.
The Day of 'Ashura
When the Messenger of Allahﷺ came to Madinah, he found the Jews at the time fasting the Day of 'Ashura. He asked them why they were fasting and they told him that it was the day on which Allah saved Sayyiduna Musa (peace be upon him) and his people and drowned Pharaoh and his people. Musa fasted out of gratitude to Allahﷻ and his people continued the practice after him. The Messenger of Allahﷺ told the Jews that his nation was closer to Musa (peace be upon him) than them. He then fasted that day and ordered his companions to fast (Bukhari and Muslim). He taught his nation (Ummah) to commemorate this great day, to reflect upon its connection to the previous Prophets and to seek a portion of the immense outpouring of Allah’s mercy that those Prophets received on 'Ashura.
The most important thing Prophet Muhammadﷺ taught us to do on this day is to fast. He informed us that if we do so, Allahﷻ wipes away the sins of the previous year (Muslim). We may ask: if we have already fasted the Day of 'Arafah then Allahﷻ has already erased our sins in the previous and coming year so what more can be gained from fasting Ashura? Some scholars mention that continuously fasting both days leads to a deeper erasure of one’s wrongdoings, protection from falling into sin in the future and also has the effect of wiping out the wrongdoings of one’s family and neighbours.
Why does fasting the Day of 'Arafah wipe out the sins of two years, whereas fasting the day of 'Ashura only wipes out the sins of one year? One reason, the scholars say, is that the Day of 'Arafah is a day attributed to Sayyiduna Muhammadﷺ which is clearly superior to 'Ashura which is attributed to Sayyiduna Musa (peace be upon him). The Messenger of Allahﷺ also taught his nation (Ummah) to fast the day before or the day after so that our tradition be distinct from the tradition of the Jews of that time.
We should renew our repentance on 'Ashura. The Messenger of Allahﷺ said that it is a day on which Allahﷻ allowed a certain people to repent and He will continue to allow others to do the same (Tirmidhi).
The Prophet Muhammad ﷺ also taught us that if someone spends generously on their family on the Day of 'Ashura, Allah will treat them with generosity for the rest of the year (Bayhaqi). It has likewise been narrated that the one who gives charity on this day will have the reward of a whole year’s charity.