How does Saiawush prove his innocence when accused of trying to seduce his stepmother?

He rode through a fire and was not burned in any manner.

He challenges his father to do battle one$-$on$-$one to answer the charge.

He attacks his step$-$mother and forces her to tell the truth.

He asks Rustem to talk with his father and explain the situation, which is that his step$-$mother is trying to seduce him.