Narrated Abu Musa:
When the Prophet (ﷺ) arrived at Medina, he noticed that some people among the Jews used to respect Ashura' (i.e. 10th of Muharram) and fast on it. The Prophet (ﷺ) then said, "We have more right to observe fast on this day." and ordered that fasting should be observed on it.
Reference | : Sahih al-Bukhari 3942 |
In-book reference | : Book 63, Hadith 166 |
USC-MSA web (English) reference | : Vol. 5, Book 58, Hadith 278 |
(deprecated numbering scheme) |