Imam Ibn Rajab Al-Hanbali (d. 795 AH), may Allah be pleased with him, declared about the first month, Muharram:
An-Nasa’ii collected a hadith narrated by Abu Dhar who said, “I asked the Prophet, peace and blessings of Allah be upon him: Which night is best? Which months are the most virtuous and noble?”
The Prophet, peace and blessings of Allah be upon him, said, “The best night is in the middle portion or the dead of the night. The best of the months is the month of Allah which you call Al-Muharram.”
The main thrust of this hadith is the best of the months is referring to what is after Ramadan as is in the narrative that is authentic.
Sa`id ibn Jubair and others narrated that the best of the sacred months is Dhul Qa`dah or Dhul Hijjah. But it was been said that the best of months in general are these months. We will discuss this topic when the subject presents itself later on, if Allah, Mighty and Majestic, wills.
Some of the Shafi`iis have said that the best of the sacred months is Rajab but this is a rejected statement. The best is the Month of Allah, Al-Muharram and in particular the first ten days.
Yaman ibn Raab claimed that these are the first ten days that he swore by but the authentic position is that the ten days He swore by in the Qur’an are the first ten days of Dhul Hijjah. This will be mentioned when the topic presents itself, if Allah, Exalted be He, wills.
Abu `Uthman An-Nahi said, “The people used to honour three ten day periods: the last ten days of the month of Ramadan, the first ten days of Dhul Hijjah and the first ten days of Al-Muharram.”
This statement is in some of the manuscripts of the Book of the Virtues of the Ten by Ibn Abid-Dunya as narrated from Abu `Uthman from Abu Dhar who narrated that the Prophet, peace and blessings of Allah be upon him, used to honour three ten day periods. This statement is not preserved though.
It has been said that the ten which Allah completed his speech with Musa, peace be upon him, were forty nights and that He spoke with that Prophet in the last ten. It is narrated from Wahb ibn Munabbih who said,
“Allah, Exalted be He, revealed to Musa, peace be upon him, in which he said, ‘Order your people that they repent to Me in the first ten days of Al-Muharram. When it is the tenth day, let them come out to Me and I will forgive them.’ ”
It is narrated from Qatadah that the Fajr which Allah swore by in the opening of Surat ul-Fajr is the Fajr of the first day of Al-Muharram that opens the year. So this is the best of the holy months after Ramadan or in general.
The fast in this is praiseworthy as the Prophet, peace and blessings of Allah be upon him, commanded it and one of the months is the end of the lunar year. One of the holy months is the opening.
Source: Lata’if ul-Ma`arif Fima Li-Mawasim il-`Ami Min Al-Waza’if, pp. 35-38