Muwatta Malik 665
موطأ مالك#665SahihYahya related to me from Malik from Ibn Shihab that Humayd ibn Abd ar-Rahman ibn Awf heard Muawiya ibn Abi Sufyan say from the mimbar on the day of Ashura in the year in which he made the hajj, "People of Madina, where are your learned men? I heard the Messenger of Allah, may Allah bless him and grant him peace, say about this day, 'This is the day of Ashura, and fasting it has not been prescribed for you. I am fasting it, and whoever of you wants to fast it can do so, and whoever does not want to, does not have to
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Salim al-HilaliSahih
In-book reference: 18:36