Are there meritorious characteristics specific to Rajab?
15-6-2014 | IslamWeb
Question:
What is special about the month of Rajab? How authentic are the hadiths stating that actions are raised to Allah in this month?
Answer:
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
Rajab is one of the sacred months about which Allah Almighty Says (what means): {Indeed, the number of months with Allah is twelve [lunar] months in the register of Allah [from] the day He created the heavens and the earth; of these, four are sacred.}[Quran 9: 36] Rajab, which is called 'Rajab The Single', does not occur in sequence with the other three months that come in succession of one another (Thul-Qa‘dah – Thul-Hijjah - Muharram). Rajab is also called “Rajab of Mudhar” because the tribe of Mudhar used to venerate and respect it so much. It is narrated on the authority of Abu Bakrah 
that the Prophet, sallallaahu ‘alayhi wa sallam, said:
Time has turned back to the same as it was on the day when Allah created the heavens and the earth. The year is twelve months, of which four months are sacred, three thereof come consecutively and these are Thul-Qi’dah, Thul-Hijjah, and Muharram. Then, the fourth month is Rajab of Mudhar, which comes between Jumadah and Sha’ban. [Al-Bukhari and Muslim]
In Pre-Islamic era of ignorance, people used to offer sacrifices during this month as an act of worship towards their idols. This type of sacrifice was called “‘Ateerah”. When Islam came, it cancelled such a practice. The Prophet, sallallaahu ‘alayhi wa sallam, said: “No Fara’, No ‘Ateerah!” [Al-Bukhari and Muslim] Also, there is no authentic evidence to support the observance of specific acts of worship in the month of Rajab, as believed by some people.
Shaykhul Islam, Ibn Taymiyyah 
said: “There is no authentic statement by the Prophet, sallallaahu ‘alayhi wa sallam, about the virtue of worship in Rajab. Rather, most of the Hadiths in this regard are false.” Ibn Hajar says, “There is no authentic hadith that can be used as evidence of a special merit of the month of Rajab, of fasting it, of fasting certain days thereof, or of offering Qiyam (voluntary night prayer) prayer on a certain night thereof.”
However, there is nothing wrong if a Muslim, during Rajab, observes the fasts that he regularly observes during other months. Examples include Mondays, Thursdays, the 13th, 14th, and 15th of every lunar month, and the habit of fasting every other day, provided that this is not done in this month in specific.
Allah Knows best.