“Verily, the number of months with Allaah is twelve months (in a year), so it was ordained by Allaah on the Day when He created the heavens and the earth; of them, four are sacred. That is the right religion, so wrong not yourselves therein…” [al-Tawbah 9:36]

Muharram is so called because it is a sacred (muharram) month and to confirm its sanctity.

Abu Hurayrah (may Allaah be pleased with him) said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘The best of fasting after Ramadaan is fasting Allaah’s month of Muharram.’” (reported by Muslim, 1982).

The phrase “Allaah’s month”, connecting the name of the month to the name of Allaah in a genitive grammatical structure, signifies the importance of the month. Al-Qaari said: “The apparent meaning is all of the month of Muharram.” But it was proven that the Prophet (peace and blessings of Allaah be upon him) never fasted any whole month apart from Ramadan, so this hadeeth is probably meant to encourage increasing one’s fasting during Muharram, without meaning that one should fast for the entire month.