Husband keeps undermining my parenting with our daughter

Me and my husband have a 4 year old daughter and lately she's been getting in trouble in prek because she thinks hitting us funny. There's this little boy who's very sweet and she has been hitting him. She lied to me about it and said he's her friend and she didn't hit him. I caught her hitting him when I picked her up and I try to tell her "Jena, we don't hit our friends." The problem is my husband thinks it's hilarious and tells her good for her for beating up the boys. I told him she needs to know hitting is wrong. He said "Well what did the boy do?" He didn't do anything. She's just been thinking it's funny and I promised the teacher we would work on the behavior. My husband has been taking it seriously at all and even told her to beat him up good at school. I told him to stop. He said he's joking. She's 4. She doesn't get joking. I'm trying so hard to break this hitting thing because I'm sure the boy doesn't like it and my husband keeps thinking it's fine. Acting like it's funny and telling her to keep doing it.