It wasnarrated that 'Aishah said:
"The Messenger of Allah (ﷺ) usedtofast 'Ashura', and he ordered (others) to fast it too." (RU)
English reference (RU): Vol. 1, Book 7, Hadith 1733 (RU)
Arabic reference (RU): Book 7, Hadith 1805 (RU)