Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates that the people of the Age of Ignorance used to fast on the day of Ashura. Then, when the obligation of Ramadan was revealed, the Messenger of Allah (peace and blessings be upon him) was asked about it. He said: "It is one of the days of Allah, so whoever wishes may fast, and whoever wishes may leave it."