Reminder! Only a few days remain until the day of Ashura, brothers. The fasting on this day erases the sins of the previous year.
Ibn Abbas, may Allah be pleased with him, was asked about observing of fast on the day of Ashura, whereupon he said: "I do not know Allah's Messenger (ﷺ) singling out any day's fast and considering it more excellent than another, except this day (the day of Ashura) and this month, meaning the month of Ramadan."
Source: Ṣaḥīḥ Muslim 1132a
Abu Qatadah reported: The Prophet, peace and blessings be upon him, was asked about fasting the day of Arafat and he said, "It will expiate the sins of the previous and upcoming years." Then, the Prophet was asked about fasting the day of Ashura and he said, "It will expiate the sins of the past year."
Source: Ṣaḥīḥ Muslim 1162