Humaid bin Abdur Rahman narrates that I heard Muawiyah bin Abi Sufyan (may Allah be pleased with him) on the day of Ashura while he was seated on the pulpit of the Messenger of Allah ﷺ. He took out a handful of hair from his sleeve and was saying, "O people of Medina! Where are your scholars? I heard the Messenger of Allah ﷺ forbidding such practices and saying, 'Indeed, the Children of Israel were destroyed when their women began to do this.'" Then he said: "I heard the Messenger of Allah ﷺ regarding this day, he said: 'I am fasting today, so whoever among you wishes may fast.'"
Hadith Referenceمسند الإمام الشافعي / كتاب الصيام / 630
Hadith Takhrijاخرجه مسلم، الصيام، باب صوم يوم عاشوراء (1129)۔