Sahih Muslim, 2651

Alqama reported that Ash'ath b. Qais went to Ibn Mas'udd while he was eating on the day of Ashura. Thereupon he said:Abu Abd al-Rahman, it is the day of 'Ashura (and you are eating). Upon this he said: Fast was observed on (this day) before the (fasting) in Ramadan was made obligatory, but when it was made obligatory, (fasting on the day of 'Ashura) was abandoned. So if you are not fasting, then take food

Rapporté par ‘Alqama : Al-Ash’ath ibn Qais alla voir Ibn Mas’ud alors qu’il mangeait le jour de ‘Ashura. Il lui dit : « Abu Abd al-Rahman, c’est le jour de ‘Ashura (et tu manges). » Ibn Mas’ud répondit : « On jeûnait ce jour-là avant que le jeûne de Ramadan ne devienne obligatoire. Mais quand il est devenu obligatoire, le jeûne de ‘Ashura a été abandonné. Donc, si tu ne jeûnes pas, mange. »