The Book of Fasting (Kitab Al-Sawm)

Muslim :: Book 6 : Hadith 2523

Abu Musa reported that the people of Khaibar (most of them were Jews) observed fast on tht day of 'Ashura and they treated it as 'Id and gave their women ornaments and beautiful dresstowear. The Messenger of Allah (may peace be upon him) said: You (only) observe fast on this day.