“Verily, the number of months with Allah is twelve months (in a year), so was it ordained by Allah on the Day when He created the heavens and the earth; of them four are Sacred, (i.e. the 1st, the 7th, the 11th and the 12th months of the Islamic calendar). That is the right religion, so wrong not yourselves therein.”
Qur’an [9:36]
The Virtue of the Four Sacred Months
Praise be to Allah, the Lord of the Worlds, and blessings and peace be upon our Prophet Muhammad, the Seal of the Prophets and Leader of the Messengers, and upon all his family and companions.
The sacred months are: Muharram, Rajab, Dhul-Qa’dah & Dhul-Hijjah (the 1st, the 7th, the 11th and the 12th months of the Islamic calendar respectively).
Al-Bukhaari (4662) and Muslim (1679) narrated from Abu Bakrah (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) said: “The year is twelve months, of which four are sacred: three consecutive months, Dhul-Qa’dah, Dhul-Hijjah and Muharram, and Rajab Mudar which comes between Jumaada and Sha’baan.”
These months are called sacred for two reasons:
1- Because fighting therein is forbidden unless initiated by the enemy.
2- Because transgression of the sacred limits therein is worse than at other times.
Hence Allaah has forbidden us to commit sins during these months, as He says (interpretation of the meaning):
“wrong not yourselves therein.” [9:36]
Although committing sins is haraam and forbidden during these months and at other times, in these months it is more forbidden.
It was narrated that Ibn ‘Abbaas said, concerning the words of Allah “so wrong not yourselves therein” [9:36]: (The command not to wrong yourself) applies in all months, then Allah singled out four months and made them sacred, and emphasised their sanctity, and He made sin during these months more grave, and He made righteous deeds and the reward thereof greater. Qataadah said, concerning the words “so wrong not yourselves therein”: Wrongdoing during the sacred months is more serious and incurs a greater burden of sin than in other months. Wrongdoing is a serious matter in any circumstances, but Allah makes whatever He wills of His commands carry more weight. And he said: Allah has chosen elites from His creation: from among the angels He chose Messengers, from among mankind He chose Messengers, from among speech He chose remembrance of Him (dhikr), from among spaces on earth He chose the mosques, from among the months He chose Ramadan and the sacred months, from among days He chose Friday (Jumu‘ah), and from among nights He chose Laylat al-Qadr. So venerate that which has been chosen by Allah, for people of understanding and wisdom respect that which has been chosen by Allah.
[ End quote from Tafseer Ibn Katheer (may Allah have mercy on him), commentary on Soorat at-Tawbah verse 36 ]
Al-Sa’di (may Allaah have mercy on him) said (p. 373):
In the phrase “wrong not yourselves therein”, the pronoun may be understood as referring to twelve months. Allaah states that He has made them a measure of time for His slaves, which they may use for worshipping Him, and thank Allaah for His blessings, and they serve the interests of His slaves, so beware of wronging yourselves therein.
The pronoun may also be understood as referring to the four sacred months, and this forbids them to wrong themselves in those months in particular, as well as it being forbidden to do wrong at all times, because it is more forbidden at this time, but it is worse at this time than at others.
The Month of Muharram (The 1st month the Islamic calendar)
The month of Allah Muharram is a great and blessed month. It is the first month of the Hijri year and is one of the four sacred months.
It was narrated that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “The best fast after Ramadan is in the month of Allah Muharram.” [Muslim]
The phrase “the month of Allah (shahr Allah)” is indicative of the veneration this month deserves, as it is attributed to Allah (in a genitive or idaafah phrase). Al-Qaari said: What appears to be the case is that what is meant is the entire month of Muharram.
But it is proven that the Prophet (blessings and peace of Allah be upon him) never fasted any month in full apart from Ramadan. So this hadeeth is to be understood as meaning that it is encouraged to fast a great deal during the month of Muharram, not to fast the entire month.
“It is proven that the Prophet (blessings and peace of Allah be upon him) fasted a great deal during Sha‘baan, and perhaps the virtue of Muharram was not revealed to him until the end of his life, before he was able to fast during this month.” [Sharh an-Nawawi ‘ala Saheeh Muslim]
There is no special virtue in fasting all or part of the month of Rajab (The 7th month the Islamic calendar)
What some people do, singling out some days of Rajab for fasting, believing that they are better than others, has no basis in sharee’ah.
But there is a report from the Prophet (peace and blessings of Allaah be upon him) which indicates that it is mustahabb to fast during the sacred months (and Rajab is one of the sacred months). The Prophet (peace and blessings of Allaah be upon him) said: “Fast some days of the sacred months and not others.” ; classed as da’eef (weak) by al-Albaani in Da’eef Abi Dawood.
Even if this hadeeth were saheeh, it indicates that it is mustahabb to fast during the sacred months. So if a person fasts during Rajab because of this, and he also fasts in the other sacred months, there is nothing wrong with that. But singling out Rajab for fasting is not right.
Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) said in Majmoo’ al-Fataawa (25/290):
As for fasting in Rajab in particular, the ahaadeeth concerning that are all da’eef (weak), and in fact mawdoo’ (fabricated). The scholars do not rely on any of them. They are not among the da’eef ahaadeeth which have been narrated concerning virtues, rather most of them are fabricated and false. In al-Musnad and elsewhere there is a hadeeth which says that the Prophet (peace and blessings of Allaah be upon him) enjoined fasting the sacred months, namely Rajab, Dhu’l-Qa’dah, Dhu’l-Hijjah and Muharram, but this has to do with fasting during all of them, not just Rajab.
Ibn al-Qayyim (may Allaah have mercy on him) said in al-Manaar al-Muneef:
Every hadeeth which mentions fasting in Rajab and praying during some of its nights is false and fabricated.
And Almighty Allah chooses whatever He wills of times and places.
[ Sources: https://islamqa.info/en/204142 , https://islamqa.info/en/75394 ]