Sahih Muslim
1132.01

Ibn Abbas was asked about observing of fast on the day of Ashura, whereupon he said:I do not know Allah's Messenger (ﷺ) singling out any day's fast and considering it more excellent than another, except this day (the day of Ashura) and this month, meaning the month of Ramadan

1132.02

A hadith like this has been narrated on the authority of 'Ubaidullah b. Abi Yazid