And Hamzah ibn Sha'bah stated in Kitab Hujjat al-Arif: 'The Iblis of every human being is their own physical temperament and the internal turbidness [al-kadar] residing within them. However, it exists in varying degrees of intensity, for this is a shared baseline in which both the believer and the disbeliever participate. Yet, alongside active disbelief, the internal Light is utterly inverted [yastahilu al-nur] and transforms into absolute darkness due to the total dominance of the physical temperament and turbidness over him—and that is because he rejected the Truth despite possessing prior knowledge of it by the pathway of true guidance. Consequently, his temperament was fundamentally inverted into absolute turbidness [al-kadar] so that he became an active Iblis, and the turbidness totally overwhelmed the Light until his entire being became dark density. As for the believers, though they are inherently mixed with this material turbidness, they have been granted absolute security against a fundamental inversion from Light to darkness; rather, they can invert from darkness back to Light.

Then he stated: 'Every turbid temperament [mizaj kadir] is the literal Iblis of its respective owner.