Muharram is the first month of the Hijri calendar and one of the four "sacred months" mentioned in the Quran. It marks the beginning of the Islamic year, dated from the Hijra (migration) of the Prophet (peace be upon him) from Mecca to Medina in 622 CE.
The Day of ʻAshura
The 10th day of Muharram is the Day of ʻAshura. The Prophet (peace be upon him) said it is the day on which Allah saved Musa (Moses) and his people from the pharaoh. He fasted it himself and recommended others to do so.
How to fast it
It is recommended to fast ʻAshura and pair it with either the 9th or the 11th of Muharram, in order to differ from the practice of fasting only the 10th. The Prophet (peace be upon him) intended to fast the 9th the following year before he died.
What is not from the Sunnah
Lamentation, self-harm, lighting bonfires, applying kohl as a ritual, or treating the day as a celebration are not from the practice of the Prophet (peace be upon him) or his companions.
Source
Summarized from IslamQA — Muharram and ʻAshura (retrieved 2026-05-09).