The importance of Rajab, the sacred month

The Sacred months have a special status, which applies also to Rajab because it is one of these sacred months.

Allaah says (interpretation of the meaning):

"O you who believe! Violate not the sanctity of the Symbols of Allaah, nor of the Sacred Month…"
[al-Maa'idah 5:2]

This means: do not violate their sanctity which Allaah has commanded you to respect and forbidden you to violate, for this prohibition includes both evil deeds and evil beliefs.

Allaah says (interpretation of the meaning):

"so wrong not yourselves therein…" [al-Tawbah 9:36] meaning, in the Sacred Months.

The pronoun here [translated here as "therein"] refers to these four sacred months, as stated by the Imaam of the Mufassireen, Ibn Jareer al-Tabari (may Allaah have mercy on him).

So we should pay attention to the sanctity of these four months, because Allaah has singled them out for a special status and has forbidden us to commit sins out of respect for their sanctity, for sins committed at this time are even worse, because of the sanctity of the time which Allaah has made sacred. Hence in the aayah quoted above, Allaah has forbidden us to wrong ourselves even though this – i.e., wronging ourselves, which includes committing sins – is forbidden during all the months of the year.

http://www.islam-qa.com/en/ref/books/111