It is narrated from Umm al-Mu'minin Sayyida Aisha (may Allah be pleased with her), she said: In the days of ignorance, people used to fast on the day of Ashura, and the Messenger of Allah (peace and blessings be upon him) also used to fast on this day during the time of ignorance. Then when the Messenger of Allah (peace and blessings be upon him) came to Madinah, he fasted on this day and ordered the people to fast on this day as well. Then when Ramadan was made obligatory, only the fasts of Ramadan remained obligatory, and the fast of Ashura was abandoned, so whoever wishes may fast on this day and whoever wishes may leave it.