The term אונאה was used twice in פרשת בהר. The word אונאה refers to a form of mistreating or belittling someone.
One type is referred to as
which is taking advantage of someone in money matters. When selling movable items, one should not make a profit of more than one sixth which is called שתות.
The other type is אונאת דברים, which is mistreatment with words. The typical example is that it is forbidden to remind someone that he is a convert. Or, remind someone that he is a Baal Teshuva, in order to make that person feel small.
It is important for us to put emphasis on laws such as these, that teach proper moral and ethical behavior.