He says that he once had a student who swore that he would fall off a cliff if he violated his oath; the student later fell to his death from a tall building. That's what you get when you break your word.
他舉例，過去他曾有一位學生以墜落山崖起誓，後來卻自高樓失足而亡，就是違反誓約遭到報應。