EXOD794 We are obligated to return lost objects to their owner. Rabbi Naftoli Tzvi Yehuda Berlin points out in his commentary that the Torah stresses the obligation to return a lost object to your enemy. By enemy the Torah means someone who usually insults you. You might think that you should keep a distance from this enemy and not come into contact with him by returning his belongings. The Torah therefore emphasizes that even in the case of an enemy, you must return what is rightfully his. Furthermore, because of the merit of this mitzvah, he might not insult you in the future. Even if he does insult you, however, you should display restraint. (Haamek Dovor, on this verse). The laws pertaining to lost articles are complex and a halachic authority should be consulted whenever any questions arise. [The author lists and explains 23 basic laws of this commandment].