Alqamah says: I came to Sayyiduna Ibn Mas'ud (may Allah be pleased with him) on the day of Ashura, and there was a bowl of tharid and meaty bones placed before him. I asked: "O Abu Abd al-Rahman! Is this not the day of Ashura?" He said: "Yes. We used to fast it with the Messenger of Allah (peace and blessings be upon him) before Ramadan was made obligatory; when Ramadan was made obligatory, it abrogated it." Then he said: "Sit down." So I sat and ate.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9953