Question 9: What is the ruling on observing Sawm (Fast) on the Day of ‘Ashooraa’ (10th of Muharram)? Is it better to observe Sawm on the day that precedes it, the day that succeeds it, all the three days, or on the Day of ‘Ashooraa’ only? Please clarify the matter. May Allaah reward you with the best!
Answer: It is a Sunnah (supererogatory act of worship following the example of the Prophet) to observe Sawm on the Day of ‘Ashooraa’ for the authentic Hadeeths in which the Prophet (peace be upon him) stated so. The Prophet (peace be upon him) mentioned that the Jews used to observe Sawm on that Day because it was the day on which Allaah (Exalted be He) rescued Prophet Moosaa (Moses, peace be upon him)and his people and destroyed Pharaoh and his people. Our Prophet Muhammad thus, observed Sawm on the Day of ‘Ashooraa’ to express his gratitude to Allaah, advised Muslims to do so, and directed us as well to observe Sawm on the day preceding or succeeding it... read more here.