The 302nd prohibition is that we are forbidden from hating one another.

The source of this commandment is G‑d's statement,1 "Do not hate your brother in your heart." In the words of the Sifra, "I have only spoken [in this verse] about hatred, which is in the heart. But if you reveal to him this hatred and he realizes that you hate him, you do not transgress this prohibition.2 But you do transgress the prohibitions,3 'Do not take revenge nor bear a grudge,' and a positive commandment, namely,4 'You must love your neighbor as [you love] yourself.'" However, the sin of hatred in one's heart is most serious of them all.