Chapter: Whoever eats on'Ashura, let him refrain (from eating) for the rest of the day
Salama b. al-Akwa' (Allah be pleased with him) reported that the Messenger of Allah ( صلی اللہ علیہ وسلم ) sent a person of the tribe of Aslam on the day of 'Ashura and commanded him to declare to the people to observe fast in case they had not observed it, and to complete fast till evening if they had taken food
Authentic