Muharram is the first month of the Hijri calendar and marks the beginning of the Islamic year.
the Prophet PBUH referred to it as ‘the Sacred Month of Allah’ being a highly blessed month.
The word ‘Muharram’ means ‘forbidden’. It is so sacred that certain actions become forbidden during it, as they would violate its sanctity. Both the month of the Muharram and Allah’s House (Al-Masjid Al-Haram) derive their names from the same Arabic root word
Allah divided the year into seasons. Some of these seasons are more sacred, spiritually, than others. The nights of Ramadan and the days of Dhul Hijjah, for instance, are clearly stated to be superior to other days and nights of the year. We know from the Quran that Muharram is one of the four sacred months.
"Surely the reckoning of months, in the sight of Allah, is twelve months,laid down in Allah’s decree on the day when He created the heavens and the earth; and out of these months four are sacred. That is the true ordainment. Do not, therefore, wrong yourselves, with respect to these months"
Surah At-Tawbah [9:36]
These four months are the months of Zulqadah, Zulhijjah, Muharram and Rajab. the Prophet in his sermon on the occasion of his last Hajj, has declared:
"One year consists of twelve months, of which four are sanctified months, three of them are in sequence; Zulqadah, Zulhijjah, Muharram, and the fourth is Rajab."
Historically, one of the practical consequences of Dhul-Qa’dah, Dhul-Hijjah and Muharram being sacred was that pilgrims would be allowed to perform Hajj safely without worrying about banditry or war. Fighting was forbidden during Dhul-Qa’dah, when they would be travelling to make the Hajj; Dhul-Hijjah, when they would be performing Hajj in Makkah and its surroundings; and Muharram, when they would be returning home from Hajj. This standard was upheld by the Arabs in pre-Islamic times, and Allah confirms it in the Quran
The 10th day of Muharram, called Ashura, is an important day for Muslims. It marks the day Nuh (Noah) left the Ark, and the day that Prophet Musa (Moses) was saved from the Pharaoh of Egypt by God, crossing the Red Sea with his people.
The Prophet said that fasting on the day of Ashura expiates the minor sins of the past year’ (Muslim)
The Prophet (saw) also advised us to also fast on the 9th and/or 11th of Muharram in order to differentiate between his Ummah and the People of the Book.