Musar zu Tehillim 139:21

There is a hatred that is a mitzvah: for example, a wicked man who will not accept correction — it is a command of the Torah to hate him, as it is said: "The fear of the Lord is to hate evil" (Prov. 8:13). And it says: "Lo, I hate them O Lord that hate Thee and I strive with those that rise up against Thee, I hate them with the utmost hatred; they are my enemies" (Ps. 139:21-22).And a man should hate lies and falsehood. The end of the matter is this — that a man should hate everything which separates him and holds him back from loving the Creator of All, as it is said: "I hate every false way" (Ibid. 119:128). And this is a great general rule, that a man should hate every false thing, and every act which will increase hatred for false ways will increase love for Torah" (Ibid 163). And let each person love truth and peace as it is written: "Therefore, love ye truth and peace" (Zech. 8:19).

If you have done a thing against your companion, regret it and go and appease him and if your companion has wronged you and regrets it, — welcome him. Even though you doubt that he is sorry in his heart and believe that he wants only to seem sincere in your eyes, — welcome him. If you have rebuked him with harsh words until he hates you as David said "And do I not strive with those that rise up against Thee?" (Ps. 139:21), do not regret such a quarrel and do not seek his forgiveness, for if you do express remorse and plead for forgiveness he will continue to err.

This is what king David, peace be unto him, said: "O G-d, do I not hate those who hate You? Do I not contend with those who rise up against You? I hate them with an utter hatred; I count them my enemies" (Tehilim 139:21-22). And Eliyahu said: "I have been very jealous for G-d, the L-rd of hosts..." (I Kings 19:10). We already learned what he merited by virtue of his jealousy for G-d, as the Torah states: "because he was jealous for his God and made atonement for the children of Israel" (Bamidbar 25:13).