Actions speak louder than words because they require more effort than words. One noticing an action will probably remember it more than hearing something similar.
Also, showing someone instead of telling someone helps one better understand a concept in school or work, for instance.
(Think about this; What is the point of someone saying that they will do something when they never do it?) There is a point being made to the person listening: that person won’t do what they say.
Good luck!