question #2 Sahih al-Bukhari 2003, Book 30, Hadith 108 : What options do Muslims have regarding fasting on the day of ‘Ashura’?

That he heard Muawiya bin Abi Sufyan on the day of ‘Ashura’ during the year he performed the Hajj,
saying on the pulpit, “O the people of Medina! Where are your Religious Scholars? I heard Allah’s
Apostle saying, ‘This is the day of ‘Ashura’. Allah has not enjoined its fasting on you but I am fasting
it. You have the choice either to fast or not to fast (on this day).’ ”