Alhamdulillah - we have just entered the month of Rajab. This is one of the sacred months which Allah (swt) mentions in the Qur'an:
"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. That is the right religion, so wrong not yourselves therein" [TMQ 9:36]
Allah (swt) says in the above ayah that four of the twelve months are sacred. We know from the aHadith that one of these four sacred months is Rajab.
Abu Bakrah (ra) narrated that the Prophet (saw) said: "The year is twelve months, of which four are sacred: three consecutive months, Dhu'l-Qa'dah, Dhu'l-Hijjah and Muharram, and Rajab Mudar which comes between Jumaada and Sha'baan." [Bukhari 4662 and Muslim 1679]
Fighting in these months has been forbidden unless it was initiated by the enemy. Also, the 'ulema have said that a haram act in these months in particular carry a greater sin due to the saying of Allah (swt) "so wrong not yourselves therein".
Furthermore, there is a narration from the Prophet (saw) which indicates that it is mandoob (recommended) to fast during the sacred months (and Rajab is one of the sacred months). The Prophet (saw) said: "Fast some days of the sacred months and not others." [Abu Dawood 2428] (There may be some disagreement on the authenticity of this narration).
It is recommended to fast on the 13th, 14th and 15th of any Islamic month:
It was narrated that Abu Dharr said: The Messenger of Allah (saw) said to me: "If you fast any part of the month, then fast the thirteenth, fourteenth and fifteenth." [Tirmidhi (761); al-Nasaa'i (2424)]
It is also recommended to fast Mondays and Thursdays of any Islamic month:
Abu Hurayrah (ra) reported that the Prophet (saw) used to fast on Monday and Thursday. On being asked about that the Prophet (saw) said: "Deeds are presented on every Monday and Thursday. Allah forgives every Muslim or every believer, except for those who are forsaking each other. He says [about them]: 'Leave them.' " [Ahmad]
This email is only meant as a reminder as the Islamic months can go by without us realising how precious our time is in this life is. So please look into this issue with those whom you trust. There is no difference amongst the 'ulema that Rajab is one of the four sacred months mentioned in the Qur'an. So may Allah (swt) give us all the tawfeeq to seek the blessings of this month, stay away from what He (swt) has forbidden and forgive us our sins.