The Prophet ﷺ used to instruct his Companions (may Allah be pleased with them) to fast on the Day of ‘Aashooraa’ before fasting in Ramadan was made obligatory, due to the virtues of that blessed day. In this hadeeth, ‘AbdullahNarrated Ibn ‘Abbaas (may Allah be pleased with him) that the Prophet ﷺ migrated from Makkah to Al-Madeenah, and on the following year he ﷺ found the Jews in Al-Madeenah fasting on the Day of ‘Aashooraa’, i.e., the tenth day of Muharram. He ﷺ asked them about the reason for it, and they stated that it was a blessed day when Allah, Exalted is He, rescued Prophet Moosaa (Moses) and the children of Israel from their enemy, Pharaoh, and caused him and his troops to drown in the sea. Therefore, Prophet Moosaa observed fasting on that day (to express gratitude to Allah), and when the Prophet ﷺ learned of that, he ﷺ stated that he had more claim over Moosaa than the Jews, being his fellow brother and Messenger of Allah and because he ﷺ was more obedient to Allah and adhered to the truth more earnestly than them. Therefore, he ﷺ had more right to express gratitude to Allah, Exalted is He, for saving Prophet Moosaa.This is why he ﷺ fasted on that day and commanded the Muslims to fast it, because we, Muslims, are more entitled to love and follow the example of Prophet Moosaa than the Jews, since they distorted the divine law revealed to him, while we are the true adherents of the religion of Allah, Islam, which is the very religion with which all the Prophets of Allah were sent. In addition, Narrated Ibn ‘Abbaas (may Allah be pleased with him) that the act of Sunnah in this regard is to observe fasting on the 9th and 10th days of Muharram, to be different from the Jews who fasted only on the 10th of Muharram, and this was narrated in Saheeh Muslim. Moreover, it has been reported on the authority of Qataadah (may Allah be pleased with him) that fasting on that day expiates the sins committed during the previous year, and this has also been cited in Saheeh Muslim. It is deduced from the hadeeth that it is permissible to observe fasting to express gratitude to Allah, Exalted is He, for relief from an adversity or anguish, or the facilitation of a desired attainment..