LEV713 It is a negative commandment not to take revenge from one's fellow-man as Scripture says, You shall not take vengeance [this verse]. Revenge means repaying a person who has harmed someone, according to his own act: for example, if one asked his neighbor, "Lend me your axe," and he would not lend it to him; and the next day his neighbor has to borrow something from him, whereupon he tells him, "I will not lend it to you, just as you refused me when I wanted to borrow from you." This is revenge, whereby he exacts vengeance from the other, repaying him according to his own evil action.