My son is saying he hates himself

so my son is only 4 years old and I've developed this new punishment as it were and getting him to stare at the wall and he absolutely hates it but it gets so bad that after 1 minute he starts hitting himself and saying he hates himself. I'm super worried about this I'm guessing he must of learnt this from somewhere else :(. His father and I are split and he lives with parents and our son has weekly contact with him. He has an uncle who is 9 that lives there and they always play and im just wondering if he's seen it from there.Anyway I'm just worried about this. Do you think it's phase that will just pass? Also my son tries to steal his younger brothers dummy and I often catch him with it and he throughs a tantrum when I take it off him. Today I let him have it for 15 minutes and I know it's bad for his teeth but he seemed to calm right down instead of just being his cheeky then going back to naughty self. I'm wondering if maybe he's been stressing out? via /r/Parenting http://ift.tt/296PZ13