Answer:
He has to pass 3 tests.
Step-by-step explanation:
To rescue shah Kai Kaous, Rustem (a Persian hero) needs to go through three difficult moments that show that he is a hero, in addition to showing that he has great loyalty with shah Kai Kaous.
These tests begin when he needs to defeat Aulad's army to reach the place where Shah Kai Kaous is imprisoned. Rustem defeats this army with ease and when he finds the shah he is informed that to release them he will have to kill not only the deevs, but the white deev as well. These two tasks are performed by Rustem with some ease and he manages to kill all the deevs while they are sleeping.