EXOD810 While the Torah commands you to be good to this person and to retrieve his animal, nevertheless there seems to be a tacit acceptance and legitimation of his status as "your enemy." Rabbi Samuel concludes that "your enemy" in this passage refer us to someone whom you are "permitted to hate" because you personally witnessed him transgressing (since you are only one witness, this makes him "your enemy" but not a "public enemy"). Presumably, this is a case where he persists in transgressing even after he has been warned and admonished [this verse; Pesachim 113b; Rambam, Hilkhot Rotze'ah 13:14].