LEV553 Do not harbor hatred towards your fellow Jew. Concealed hatred is worse than observable hatred, so the Torah particularly warns against harboring hatred in one's heart. [He who lets his hatred show does not violate this command, but he does violate the negative commands, “Do not bear a grudge” (לא תטר) and “Do not take vengeance” (לא תקם). Moreover, he also violates the positive command, “Love your neighbor as yourself.”] … hatred in one's heart causes many serious problems between people. It gives rise to every type of slander, informing and talebearing, and no trait is more evil and abominable to any thinking person.