Abdur Rahman bin Yazid says: Ash'ath bin Qais went to Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) on the day of Ashura, while he was eating food. He said: Abu Muhammad! Come near to eat food. Ash'ath said: Is today not the day of Ashura? He said: Do you know what Ashura is? The Messenger of Allah (peace and blessings be upon him) used to fast on this day before the obligation of Ramadan was revealed. When the command of the month of Ramadan was revealed, the fast of this day was abandoned.