And from him, from Yaqub ibn Yazid, from Abu Hammam, from Abu al-Hasan عليه السلام, peace be upon him:
Imam عليه السلام said: “The Messenger of Allah سبحانه وتعالى, may Allah سبحانه وتعالى bless him and his family, fasted the day of Ashura.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 4, p. 375