Narrated Ibn `Abbas:
The Prophet (ﷺ) came to Medina 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, Moses fasted this day." The Prophet (ﷺ) said, "We have more claim over Moses than you." So, the Prophet fasted on that day and ordered (the Muslims) to fast (on that day).
Reference | : Sahih al-Bukhari 2004 |
In-book reference | : Book 30, Hadith 109 |
USC-MSA web (English) reference | : Vol. 3, Book 31, Hadith 222 |
(deprecated numbering scheme) |