Sayyiduna Abdullah bin Umar (may Allah be pleased with them) narrated that in the days of ignorance, we used to fast on the day of Ashura, but when the fasting of Ramadan was prescribed, the Prophet (peace and blessings of Allah be upon him) said: Whoever wishes may fast on Ashura, and whoever wishes may leave it.
Hadith Referenceاللؤلؤ والمرجان / كتاب الصيام / 689
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 65 كتاب التفسير: 2 سورة البقرة: 24 باب (يا أيها الذين آمنوا كتب عليكم الصيام»