Jami` at-Tirmidhi 755
جامع الترمذي#755Da'ifIbn Abbas narrated:"The Messenger of Allah ordered fasting the tenth day for the Day of Ashura
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiDaif
In-book reference: 8:74