Because the old hero obstinately refused to be manacled, the two warriors began fighting, and at the end of the day Rustem and his steed were so severely wounded that Isfendiyar felt sure they would not be able to renew the fight on the morrow.
It happened, however, that the aged Zal, on seeing his wounded son, remembered his partly burned feather, and promptly cast it into the fire.

Immediately the Simurgh appeared, and with one touch of her golden wings healed the horse, and used her clever beak to draw the lance out of Rustem's side.

Having thus healed her nursling's son, the Simurgh vanished, leaving Rustem and his steed in such good condition that they were able to renew the battle on the morrow.

This time, Isfendiyar perished beneath Rustem's blows, exclaiming that the hero was not to blame for his death and that he fell victim to his father's hate.

In token of forgiveness, he begged Rustem to bring up his son, a wish which was piously carried out by the brave warrior as long as he lived.
Because it had been written in the stars that "he who slew Isfendiyar would die miserably," Rustem was somewhat prepared for his tragic fate.