Is your son copying any one 4 year olds dont often hit their parents unless they are hit a and it is learned behavior, also the words stupid and telling you to shut up, is there a family member says this to him? Instead of focusing on the punishment aspect how about you focus on why he is behaving like this ,he sounds unhappy what can he be unhappy about?Focus on his positive side and praise him when you see him doing something right. Is he at school and how does he bahve there?
He is in daycare right now so imitation of another child may be one issue. He started saying thoses words and hitting when he got angy all of a sudden and no, we dont use those words or hit him. That's the reason he uses the words - because he knows they bother us. He is the same at school or at home for behaviour.
We praise him when he does good and he does react well to this but still reverts back to the anger.