Volume 3, Book 31, Number 117:
Narrated ‘Aisha:
(The tribe of) Quraish used to fast on the day of Ashura’ in the Pre-lslamic period, and then Allah’s
Apostle ordered (Muslims) to fast on it till the fasting in the month of Ramadan was prescribed;
whereupon the Prophet said, “He who wants to fast (on ‘Ashura’) may fast, and he who does not want
to fast may not fast.”