why was disciple choosen to suffer the punishment for the thief how does Guru manage to save his life

Dear student... The disciple was chosen for the punishment of the thief because ultimately the merchant had been decided to be the culprit by the King however he was too thin for the stake. They needed someone fat and stout hence the chose the disciple for the punishment even though it was not his fault only because he was stout. The guru saves the disciple by fooling the king and his minister. He tells them that whoever is executed first shall be the king in his next birth and whoever is executed the second shall be the minister in his next birth. The foolish king wanted to be the king in his next birth and he wanted the same minister too hence both he and minister decided to execute themselves. In this way the guru saved his disciple from being executed.....Regards