(69) باب صِيَامِ يَوْمِ عَاشُورَاءَ
Narrated Ibn `Abbas:
I never saw the Prophet (ﷺ) seeking to fast on a day more (preferable to him) than this day, the day of 'Ashura', or this month, i.e. the month of Ramadan.
Reference: Sahih al-Bukhari 2006
In-book reference: Book 30, Hadith 111
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 31, Hadith 224