The sorcerer-king of Mazandaran turns himself into a stone. When Rustam recovers from his astonishment he carries the stone on his back to Kay Kavus. He addresses the stone, threatening to break it up, whereupon the sorcerer-king reassumes his natural shape.
[Note that in some of the paintings the stone has the form of the sorcerer-king, in others it is an amorphic rock, which seems more in keeping with the text.]