The Jordanian Iftaa Department stated that it is preferable to fast more during the sacred months, including the month of Rajab.
It clarified in its response to a citizen's question about the ruling on fasting in the month of Rajab as follows:
Answer:
Praise be to Allah, and peace and blessings be upon our Prophet Muhammad
The majority of scholars from the Hanafi, Maliki, Shafi'i, and some Hanbali schools consider it recommendable to fast during the month of Rajab, just like fasting the other sacred months, which are: Muharram, Dhu al-Qi'dah, and Dhu al-Hijjah.
They base this on several hadiths, including the saying of the Prophet Muhammad when asked why he fasted during the month of Sha'ban: "That is a month which people neglect between Rajab and Ramadan" narrated by Nasai (2357). They said: This hadith indicates that the months of Rajab and Ramadan are months of worship and obedience that people should not neglect.
Other hadiths with weak chains have been cited, as stated by Hafiz Ibn Hajar, including one that goes: "Fast during the sacred months and stop" narrated by Abu Dawud. However, they said: Weak hadiths can be acted upon in matters of virtuous deeds, but caution must be exercised with fabricated hadiths reported about the virtue of Rajab.
Ibn Hajar al-Haytami, may Allah have mercy on him, said: "Many fabricated hadiths have been narrated about the virtue of fasting in it, and our Imams and others did not rely on them for recommending its fasting, far from it, rather they depended on what I have mentioned and others -and he mentioned some weak hadiths then said:- It is established that the weak, Mursal, Mawquf, Munqati, and Mua'llal hadiths can be acted upon in matters of virtuous deeds by consensus, and undoubtedly fasting in Rajab is among the virtuous deeds, so it suffices to rely on weak hadiths and the like in this regard" from "Al-Fatawa Al-Fiqhiyyah Al-Kubra" (2/54).
Moreover, it recently became renowned in the Hanbali doctrine that singling out the month of Rajab for fasting is disliked, for fear that people might think its fasting is obligatory like Ramadan, based on narrations from some of the companions.
They cited what was reported by Ibn Abi Shaybah in "Al-Musannaf" (2/345) from Khurash bin Al-Hurr who said: "I saw Umar beating the hands of people in Rajab, to put them in dishes, and he said: Eat, because it is only a month that the people of Jahiliyyah esteemed." Refer to "Al-Mughni" by Ibn Qudamah (3/53).
The answer is that Umar bin Al-Khattab, may Allah be pleased with him, intended to prevent comparing Rajab to Ramadan so that people do not believe fasting it is as obligatory as fasting Ramadan. He thus forbade some fasters whom he feared might hold that belief; it was a wise legal policy from him, may Allah be pleased with him.
Consequently, the Hanbalis, may Allah have mercy on them, stated: The dislike is removed by not fasting for one day therein, or by fasting another complete month so as not to single out Rajab for fasting.
Therefore, if one is accustomed to performing voluntary fasts, and fasts frequently in the month of Rajab hoping for reward, none of the four established schools of jurisprudence should criticize him. And Allah knows best.
