"... fasting the entire months of Rajab and Sha'ban voluntarily goes against the conduct and Sunnah of the Prophet (sallallaahu 'alaihi wasallam)" (Permanent Committee - [url=http://www.alifta.org/Fatawa/FatawaChapters.aspx?View=Page&PageID=346&PageNo=1&BookID=10]Source[/url])
"There is no authentically reported Hadith that urges to fast the month of Rajab. Therefore, it is not legislated to particularize it (the month of Rajab) to observe Sawm (fast)." (Permanent Committee - [url=http://www.alifta.org/Fatawa/FatawaChapters.aspx?View=Page&PageID=339&PageNo=1&BookID=10]Source[/url])
"As for singling out the month of Rajab for Sawm, it is also Makruh [disliked]. However, if a person observes Sawm on some of its days and breaks the Sawm on other days, there is nothing wrong with this." (Permanent Committee - [url=http://www.alifta.org/Fatawa/FatawaChapters.aspx?View=Page&PageID=338&PageNo=1&BookID=10]Source[/url])
"It is an act of Bid'ah (innovation in religion) to single out the month of Rajab for offering Salat-ul-Ragha'ib or for celebrating the 27th night which people believe to have been the night when Isra' (Night Journey) and Mi'raj (Ascension to Heaven) took place." (Shaykh ibn Baaz (may Allah have mercy upon him) - [url=http://www.alifta.org/Fatawa/FatawaChapters.aspx?View=Page&PageID=1960&PageNo=1&BookID=14]Source[/url])
"...There is nothing wrong, however, with performing 'Umrah (lesser pilgrimage) in the month of Rajab. It was authentically ... that the Prophet (may Allaah grant him peace and raise his rank) performed Umrah in Rajab." (Shaykh ibn Baaz (may Allah have mercy upon him) - [url=http://www.alifta.org/Fatawa/FatawaChapters.aspx?View=Page&PageID=1960&PageNo=1&BookID=14]Source[/url])
[url=http://www.alifta.org/Fatawa/FatawaChapters.aspx?View=Tree&NodeID=343&PageNo=1&BookID=10]List of Rajab Fatawaa[/url]