al-Haafiz Ibn Rajab al-Hanbali rahimahullah was born in Baghdad in 736H. He studied in Egypt and Damascus where he settled down until he died. He was a devoted student of Hadeeth and was one of the most prominent students of Ibn al-Qayyim rahimahullah and al-Haafiz al-Iraqi rahimahullah.
The following extract accompanied by the actual scan from the book of Ibn Rajab rahimahullah, Lata'if al-Ma`arif fi ma li Mawasim al-`Am min al-Waza'if, will show that using quotes from the great Imam as evidence to support the celebration of Nisfu Sha'baan is either ignorance or extracting selectively to mislead others.
Among the innovations that have been invented by some people is celebrating the middle of Sha'baan (Laylat al-Nusf min Sha'baan), and singling out that day for fasting. There is no evidence (daleel) for that which can be regarded as reliable. Some da'eef (weak) ahaadeeth have been narrated concerning its virtues, but we cannot regard them as reliable. The reports which have been narrated concerning the virtues of prayer on this occasion are all mawdoo' (fabricated), as has been pointed out by many of the scholars. We will quote some of their comments below, insha Allaah.
Some reports have also been narrated on this matter from some of the salaf in Syria, and others. What the majority of scholars say is that celebrating this occasion is an innovation, and that the ahaadeeth concerning the virtues of this occasion are all da'eef (weak), and some of them are mawdoo' (fabricated). Among those who pointed this out was al-Haafiz Ibn Rajab, in his book Lataa'if al-Ma'aarif, and others. The da'eef ahaadeeth concerning acts of worship can only be acted upon in the case of acts of worship which are proven by saheeh evidence. There is no saheeh basis for celebrating the middle of Sha'baan, so we cannot follow the da'eef ahaadeeth either. This important principle was mentioned by Imaam Abu'l-'Abbaas Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him).
Al-Haafiz Ibn Rajab (may Allaah have mercy on him) said in his book Lataa'if al-Ma'aarif concerning this matter after previously discussing it:
"Laylat al-Nusf min Sha'baan (the middle of Sha'baan) was venerated by the Taabi'een among the people of al-Shaam, such as Khaalid ibn Mi'daan, Makhool, Luqmaan ibn 'Aamir and others, who used to strive in worship on this night. The people took the idea of the virtue of this night and of venerating it from them. It was said that they heard of Israa'eeli reports (reports from Jewish sources) concerning that. Most of the scholars of the Hijaaz denounced that, including 'Ataa' and Ibn Abi Maleekah. 'Abd al-Rahmaan ibn Zayd ibn Aslam narrated that view from the fuqahaa' of Madeenah, and this was the view of the companions of Maalik and others. They said: this is all innovation.
No comment from Imaam Ahmad concerning Laylat al-Nusf min Sha'baan is known of. Concerning spending the night of the middle of Sha'baan in prayer, there is no sound report from the Prophet (peace and blessings of Allaah be upon him) or from his companions."
This is what was said by Al-Haafiz Ibn Rajab (may Allaah be pleased with him). He clearly states that there is no sound report from the Prophet (peace and blessings of Allaah be upon him) or from his companions (may Allaah be pleased with them) about Laylat al-Nusf min Sha'baan (the middle of Sha'baan).
Extracted from from Majmoo' Fataawa Samaahat al-Shaykh 'Abd al-'Azeez ibn Baaz, 2/882
Scan from Ibn Rajab's Lata'if al-Ma`arif fi ma li Mawasim al-`Am min al-Waza'if: