Allah, the Exalted, has said: "And when His manifestation appeared to the mountain, He made it crumble to dust, and Moses fell unconscious." (al-Aʿrāf 7:143) Heyemān is the loss of one's composure due to astonishment and ḥayra (perplexity). This state is, in terms of continuity, more constant, and in terms of its quality, more dominant than dehşet (awe). It has three degrees.
The first degree is the heyemān experienced at the moment when the aspirant, while aiming for the path, contemplates how base his own worth is, how low his station, and how insignificant he is in value, and perceives the initial glimmer of divine grace. The second degree is the heyemān that occurs at the moment when the flashes of fanāʾ (annihilation in God) and maʿrifa (gnosis, experiential knowledge of God) are witnessed, when His proofs become manifest, when one attains to His extraordinary wonders and the radiance of His lights, and during the clash of the waves belonging to the ocean of realization. The third degree is the heyemān experienced when it occurs in the mirror of pre-eternity, when the eternal qudra (divine power) is witnessed, and during the drowning in the ocean of unveiling. (Manāzil, 34-35)
Heyemān is the excess (that is, the overabundance) of the essential love present in all existents. This state, due to the request for the manifestations of His light from the Real (al-Ḥaqq), dominates the spirit of Prophet Abraham. Heyemān in Abraham signifies the intense flow of divine maḥabba (love) in his being. (Sofyavi, 102)