Frederick is scared of going back because he knows he will be punished. So after a few days of hiding in the woods, Frederick decides to try and escape. He knows his life will be better. He knows he's being treated badly. As he was running in the woods he found Sandy. Sandy invited him into his home because he knows how Frederick feels.
Sandy brought Frederick to a certain part in the woods. Where there was a certain root. Sandy gave Frederick the root and said, “As long as you have this root on your right side, Covey or any other slave owner will not be able to touch you.” Frederick didn't really believe the root would do this. So As Frederick was heading back to Mr.Covey's he realized that his punishment would be much worse then just getting whipped. He would have to stick up for himself, he would have to fight Covey.
As Frederick returns to the plantation Covey is furious. Covey is calling Frederick to the whipping post. Frederick is going to stand up for himself. Frederick grabs covey by the throat and hits him with the root. Frederick wins the fight and is no longer being punished by covey, because covey is to scared to lose another fight, and to a slave.