Narrated `Aisha:
'Ashura' (i.e. the tenth of Muharram) was a day on which the tribe of Quraish used to fast in the prelslamic period of ignorance. The Prophet (ﷺ) also used to fast on this day. So when he migrated to Medina, he fasted on it and ordered (the Muslims) to fast on it. When the fasting of Ramadan was enjoined, it became optional for the people to fast or not to fast on the day of Ashura.
Reference | : Sahih al-Bukhari 3831 |
In-book reference | : Book 63, Hadith 56 |
USC-MSA web (English) reference | : Vol. 5, Book 58, Hadith 172 |
(deprecated numbering scheme) |