(19) باب صَوْمِ يَوْمِ عَاشُورَاءَ
This hadith has been narrated on the authority of Zuhri with the same chain of transmitters that be heard Allah's Apostle (ﷺ) as saying on a similar day:
I am fasting today, so he who wishes to observe fast should do so; but he did not make mention of the rest of the hadith.
Reference: Sahih Muslim 1129 c
In-book reference: Book 13, Hadith 161
USC-MSA web (English) reference(deprecated numbering scheme): Book 6, Hadith 2517