I fell my husband is being abused at work?

I fell my husband is being abused at work. my husband is a very nice guy and doesnt yell. his boss takes his anger out on my husband, he yells at him and belittles him. He treats mt husband very bad and very different than everyone else, i believe it is because my husband wong yell back. it is driving me mad and i told him to report him to another boss, but he feels that once his boss finds out, along with his bosse's prefered employee, will retaliate. isnt this ilegal? what can i do?