Hadith 3622
Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: The Prophet Muhammad (peace and blessings be upon him) said regarding fasting on the day of Ashura, this was after the command of fasting in Ramadan was revealed: "Whoever wishes may fast on this day, and whoever wishes may leave it."
Hadith 3623
Sayyiduna Abdullah bin Umar (may Allah be pleased with them) narrates: The Noble Prophet (peace and blessings be upon him) said: "The day of Ashura is such a day that in the days of ignorance people used to fast on it, so whoever among you wishes to fast on this day may do so, and whoever dislikes it may leave it."