Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) came to Madinah Munawwarah and saw that the Jews were fasting on the 10th of Muharram. He asked them: "What is this day on which you fast?" They said: "This is a great blessed day. On this day Allah Almighty saved the Children of Israel from their enemy, and Musa (peace be upon him) fasted on this day." The Messenger of Allah (peace and blessings be upon him) said: "I am more deserving of Musa (peace be upon him) than you." Then he (peace and blessings be upon him) himself fasted on this day and also ordered (the Muslims) to fast on it.