Is it permissible to fast the entire month of Muharram?

There is no objection in Islamic law to fasting the entire month of Muharram, as fasting is recommended during this month as well as during the rest of the sacred months. Muharram is the most virtuous among these months, due to the hadith of the Messenger of Allah (peace and blessings be upon him) who said, “The best fast after the month of Ramadan is fasting in the month of Allah, al-Muharram” (recorded by Abu Dawud and at-Tirmidhi).

And Allah Almighty knows best