It was narrated that Ibn ‘Abbas (رضي الله عنه)(رضي الله عنه) said:

The Messenger of Allah (ﷺ) came to Madinah and saw the Jews fasting on the day of ‘Ashoora’. He said: “What is this day on which you fast?” They said: This is a good day; this is a day on which Allah saved the children of Israel from their enemies, so Moosa (عليه السلام) fasted on this day. The Messenger of Allah (ﷺ) said: “I am closer to Moosa than you.” And the Messenger of Allah (ﷺ) fasted on this day and enjoined fasting on it.