What is the origin of the idiom "a taste of one's own medicine" and when to use it?

The idiom "a taste of one's own medicine" has its origins in a proverb that dates back centuries. The proverb "He that will not hear must feel" is one of its earliest forms and implies that those who refuse to listen to advice or admonishments will eventually experience the consequences of their actions physically or emotionally. It is commonly used in situations where an individual is facing the repercussions of their own behavior, especially if that behavior involved mistreatment, deceit, or harm towards others.