Halakhah su Salmi 7:78

Whoever takes revenge on someone, violates a negative commandment, for it is written, "Do not take revenge."²⁶Leviticus 19:18. And what constitutes vengeance? Reuvein says to Shimon, "Lend me your spade!"²⁷The prohibition against vengeance is not limited to the loaning of tangible articles, it also includes requests for monetary loans, favors or charity. (Mishnah Berurah 156:4) [Shimon] replies, "No, I will not lend it to you." The next day [Shimon] has to borrow something and he says [to Reuvein]: "Lend me your spade." [Reuvein] says: "No, I will not lend it to you, just as you did not lend me [yours] when I asked you for it." This constitutes taking revenge, and he [Reuvein] has violated a negative commandment. Rather when [Shimon] comes to borrow something, he should give it to him wholeheartedly and not pay him back for what he did to him. It is becoming for a person to show forebearance in all mundane matters, for in the eyes of understanding people, they are all nothing but vanity and futility, and not worth taking revenge because of them. And thus said King David, peace be upon him,²⁸Psalms 7:5. "If I have repaid my friends with evil,²⁹The meaning of this passage becomes clear when it is read in conjuction with the next verse, “If I have repaid others with evil—then let the enemy pursue my soul.” I who released my unprovoked adversary. (For the prohibition against uttering curses, see Chapter 6: 3).

And maybe, my son, you will think to come to me with that which is written (Psalms 7:12), "and God gets furious every day" - and they, may their memory be blessed, said (Berakhot 7a), "And how much is His fury? An instant." And you, my son, should not err in this, God forbid, that there be evil to God, and that your heart believe about Him, blessed be He, anything but all perfection. And the matter of anger only happens in us from the angle of our being inferior physical beings. And in truth the fury that they mentioned about Him is only by way of analogy to a matter of the world. Their intention [with it] was to say that in that the majority of people in the world are pulled after their desires and there are many among them that worship the sun, the moon and the constellations - and even trees and stones - the world constantly becomes liable for extinction. And maybe the reason for their saying that His fury is for an instant every day is that since the world is judged according to its majority and that the world becomes liable because of their bad deeds on each and every day; they, may their memory be blessed, compared that small moment when a sinner completes the majority [of the world's actions] with his sin, to the fury of God. As everything is fit at the instant for extinction from the power of [God's] trait of justice, except that [His] trait of kindness immediately determines [otherwise] and preserves it. And accept this, my son, from me until you hear [something] better than it.