Sayyiduna Ibn Abbas (may Allah be pleased with them both) said that when the Messenger of Allah (peace and blessings be upon him) came to Madinah, he saw the Jews observing the fast of Ashura. He (peace be upon him) asked them (about its reason), so they said that on this day Musa (peace be upon him) prevailed over Pharaoh (and achieved victory). The Messenger of Allah (peace and blessings be upon him) said: "You are closer to Musa (peace be upon him), so observe the fast."

It is narrated from Sayyida Aisha (may Allah be pleased with her) that the Noble Prophet (peace and blessings be upon him) used to fast on the day of Ashura and would order us to fast as well.

It is narrated from Sayyiduna Salamah bin Akwa’ (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) sent a person from the tribe of Aslam with this message on the day of ‘Ashura:“This is the day of ‘Ashura, and whoever has eaten or drunk something should complete the fast for the rest of the day, and whoever has not eaten or drunk should observe the fast for this day.”

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: The Messenger of Allah (peace and blessings be upon him) said: "This is the day of Ashura, and the Quraysh used to fast on it during the days of ignorance. So whoever among you wishes may fast on Ashura, and whoever wishes to leave it may leave it." And Sayyiduna Ibn Umar (may Allah be pleased with them both) did not specifically fast on Ashura, except that if Ashura came during the days he was fasting, he would complete his fasts.

Umm al-Mu’minin Sayyida Aisha (may Allah be pleased with her) said: In the days of ignorance, the Quraysh used to fast on the day of Ashura. Then when the Messenger of Allah (peace and blessings be upon him) came to Madinah, he fasted on that day and ordered (the people) to fast. Then when the fasting of Ramadan was made obligatory, it became obligatory and Ashura was abandoned; whoever wished fasted and whoever wished left it.