Prince Esfandiar was invulnerable because he had bathed in sacred water; only his eyes, which he had kept closed, could be wounded. His father, King Goshtasp, promised him the throne if he brought Rostam to court in chains. Goshtasp knew Rostam would never allow it and secretly hoped his son would die in the attempt.
Esfandiar and Rostam respected each other. Rostam offered to come of his own free will, but never in chains. Esfandiar could not give up his mission. So they fought, and on the first day Rostam and Rakhsh were badly wounded. Zal burned a feather of the Simorgh. The bird healed them both and showed Rostam a tamarisk branch: from it he should make an arrow and aim at Esfandiar’s eyes. It warned him that whoever killed Esfandiar would find no happiness in this world or the next.
The next day Rostam once more begged Esfandiar for peace. When he refused, Rostam shot the arrow, which struck Esfandiar in the eyes. Dying, Esfandiar realised that his father had sent him to his death and entrusted his son Bahman to Rostam’s care. Many consider this the deepest story of the Shahnameh: there is no villain, only duty, pride and an unavoidable misfortune.