حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ، حَدَّثَنَا ابْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ كَانَ عَاشُورَاءُ يُصَامُ قَبْلَ رَمَضَانَ، فَلَمَّا نَزَلَ رَمَضَانُ قَالَ " مَنْ شَاءَ صَامَ، وَمَنْ شَاءَ أَفْطَرَ ".
Narrated `Aisha: The people used to fast on the day of 'Ashura' before fasting in Ramadan was prescribed but when (the order of compulsory fasting in) Ramadan was revealed, it was up to one to fast on it (i.e. 'Ashura') or not. Translation Not Available
Book Ref: Sahih Bukhari Book 65 Hadith 4502
Web Ref: Sahih Bukhari Vol 6 Book 60 Hadith 29