In al-Bāʿith ʿalā Inkār al-Bidaʿ wa-l-Ḥawādith (pp. 22–23), quoting Abū Bakr al-Ṭurṭūshī—may Allah have mercy on him—it is said:

“Among the practices the innovators have introduced, thereby abandoning what the jurists have prescribed and following the customs of the Magians, turning their religion into mere amusement, is the lighting of fires on the night of mid-Shaʿbān. Nothing sound concerning this night has reached us from the Messenger of Allah ﷺ. He never spoke of performing prayer during it, and not even a single trustworthy transmitter has reported the lighting of fires on that occasion. Whoever has invented this is simply trifling with the Muhammadan law and yearning for the Magian creed, for fire is their object of worship.

The practice first appeared in the era of the Barmakids: they inserted into Islam something with which to deceive the masses, making the lighting in Shaʿbān seem like a sunnah of faith, while their real aim was the worship of fire and the promotion of their own religion—the most wretched of religions. Thus, when the Muslims prayed, bowing and prostrating, they were facing the very fire that had been kindled. Years and ages passed with the custom in place; Baghdad adopted it, and the other cities followed suit. Added to this is the mingling of men and women who gather on that night. It is therefore obligatory upon the ruler to stop them and upon the scholar to restrain them.

Shaʿbān is honored only because the Messenger of Allah ﷺ used to fast during it; an authentic hadith confirms that he fasted the whole of Shaʿbān, or most of it.”

Ibn Abī Shāmah then said (p. 25):

“All of this is corruption originating with misguiding ascetics; how much worse, then, is the corruption that comes from debased sinners? They revive that night with every kind of overt and hidden sin—all because of the unusual illumination they imagine to be a devotional act, whereas in reality it is nothing but assistance in disobedience to Allah, an open display of wrongdoing, and a strengthening of the symbols of the innovators. No basis for it exists in the sacred law.”