The Serpents Spring from Zahhak

From A4.3, Zahhak Is Tempted by Iblis. It illustrates A4.3.25–30:

A4.3.25
Allow me both your shoulders to embrace,To kiss them, touch them with my eyes and face.”
A4.3.26
Zahhak discerned no trap, no hidden art,Nor guessed the evil in the tempter’s heart.
A4.3.27
Off guard, the king replied without delay:“I grant your wish, come take it while you may.”
A4.3.28
He kissed the shoulders; then beneath the groundHe vanished, and no trace of him was found.
A4.3.29
No eye had witnessed such a fearful sight;Then horror rose from shoulders left and right.
A4.3.30
From either shoulder, black and twisting, grewTwo serpents, hideous to mortal view.