Abdur Rahman bin Yazid says that once on the day of Ashura, Ash'ath bin Qais came to Sayyiduna Ibn Mas'ud (may Allah be pleased with him), who was eating at that time. He said: O Abu Muhammad! Come forward to eat. Ash'ath said: Is today not the day of Ashura? Sayyiduna Ibn Mas'ud (may Allah be pleased with him) replied: Do you even know what the day of Ashura is? Before the command of fasting in Ramadan was revealed, the Prophet (peace and blessings be upon him) used to fast on this day. When the command of fasting in Ramadan was revealed, this fast was abandoned.