Saying hurtful things in your mind in moments of anger

Is it a sin to think or say hurtful and mean things about someone in your head when you're angry, but you keep silent and do not utter those hurtful or mean things to anyone and you restrain your anger? Will Allah punish us for our thoughts? Sometimes I get angry and have to express my anger in my head, but I do not say the hurtful things that that I say in my head to anyone and I always feel remorseful for saying those things in my head after I am not angry anymore.