Humaid bin Abdur Rahman narrates that I heard Sayyiduna Muawiyah bin Abi Sufyan (may Allah be pleased with him) on the day of Ashura during Hajj, delivering a sermon from the pulpit. He said: O people of Madinah, where have your scholars gone? I heard the Messenger of Allah (peace and blessings be upon him) say: This is the day of Ashura; its fasting is not obligatory upon you, but I am fasting, so whoever wishes may fast (and act upon my Sunnah), and whoever wishes may not fast.
Hadith Referenceاللؤلؤ والمرجان / كتاب الصيام / 691
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 30 كتاب الصوم: 69 باب صيام يوم عاشوراء»
Brief Explanation
Perhaps it reached Sayyiduna Mu'awiyah radi Allahu anhu that the people of Madinah consider fasting on ‘Ashura’ to be disliked, or they do not give it due importance, or they regard it as obligatory, so he delivered this address from the pulpit. (Secret)