Ibn 'Abbaas (may Allaah be pleased with him) said: "The Prophet (peace and blessings of Allaah be upon him) came to Madeenah and saw the Jews fasting on the day of 'Aashooraa'. He said, 'What is this?' They said, 'This is a righteous day, it is the day when Allaah saved the Children of Israel from their enemies, so Moosa fasted on this day.' He said, 'We have more right to Moosa than you,' so he fasted on that day and commanded [the Muslims] to fast on that day." (Reported by al-Bukhaari)
Fasting on the day of 'Aashooraa', was obligatory but when fasting Ramadaan was made obligatory, the obligation to fast 'Aashooraa' was lifted, i.e., it was no longer obligatory to fast on this day, but it is still desirable (mustahabb).
Quoted from above
Fasting on 'Aashooraa'
Ibn 'Abbaas (may Allaah be pleased with him) said: "The Prophet (peace and blessings of Allaah be upon him) came to Madeenah and saw the Jews fasting on the day of 'Aashooraa'. He said, 'What is this?' They said, 'This is a righteous day, it is the day when Allaah saved the Children of Israel from their enemies, so Moosa fasted on this day.' He said, 'We have more right to Moosa than you,' so he fasted on that day and commanded [the Muslims] to fast on that day." (Reported by al-Bukhaari)
Fasting on the day of 'Aashooraa', was obligatory but when fasting Ramadaan was made obligatory, the obligation to fast 'Aashooraa' was lifted, i.e., it was no longer obligatory to fast on this day, but it is still desirable (mustahabb).
Quoted from above