Observing Saum (fast) on the day of Ashura (tenth of Muharram).
The Prophet (SAW) came to Al-Madina and saw the Jews fasting on the day of Ashura. He asked them about that. They replied, "This is a good day, the day on which Allah rescued Bani Israel from their enemy. So, Musa (Moses) (AS) observed Saum (fast) on this day." The Prophet (SAW) said, "We have more claim over Musa (Moses) than you." So, the Prophet (SAW) observed Saum (fast) on that day and ordered (the Muslims) to observe Saum (fast) (on that day).
