Our Gemara on Amud Beis discusses circumstances where one is obligated to assist a fellow Jew in loading and unloading his beast. The Gemara established that all things considered equal, one should assist in unloading a beast first, before assisting in loading. Logic has it, that the beast and even the owner, is in greater distress when needing to unload versus loading, since the packages might fall or the beast might become injured.
Despite this, when faced with one person whose animal needs to be unloaded, and another person whose animal needs loading, and the person whose animal needs loading is a hated person, the Torah commands that you load the hated person’s animal first. (The verse in Shemos 23:5 uses the term “hated person” in the directive in order to teach this point.) Why? The gemara says, “to subjugate his evil inclination”, that is, to overcome and moderate the impulse to act on hatred.
Who is this hated person? Elsewhere the Gemara (Pesachim 113b) observes:
But is one permitted to hate a fellow Jew? Isn’t it written: “You shall not hate your brother in your heart” (Leviticus 19:17), which clearly prohibits the hatred of another Jew?... Rather it is referring to a case like this, when he saw him perform a sinful matter. He is therefore permitted to hate him for his evil behavior, whereas others who are unaware of his actions may not hate him…Rav Naḥman bar Yitzḥak said: Not only is this permitted, it is even a mitzvah to hate him, as it is stated: “The fear of God is to hate evil” (Mishley 8:13).
If so, that it is a mitzvah to hate him, Tosafos in our Gemara wonders why is there any reason to overcome an evil inclination? Au contraire, he should hate him and not give his beast preference over another’s beast. Tosafos answers that this particular directive must be referring to a person whom you hate and is not a sinner, albeit other aspects of the mitzvah discussed in Pesachim refer to the sinner who is hated. This is a difficult peshat, because if the Gemara in Pesachim finds it unthinkable that the Torah should matter of factly refer to hating a person when it is sinful, how can our Gemara accept that? One might answer that since there are scenarios where it is permitted to hate certain Jews, this is enough to allow the Torah to casually refer to a hated person, even if some aspects of the verse are referring to an enemy that is unjustified.
The Rambam is clearly bothered by this question and has a different interpretation than Tosafos. He holds that the obligation to load the hated person first applies even to a sinner. He explains in Laws or Murder and Preservation of Life (13:13-14):
When a person encounters two individuals: one whose donkey is fallen under its load and one with a donkey whose burden has been unloaded, but who cannot find anyone to help him reload it, it is a mitzvah to unload the fallen donkey first, because of the discomfort suffered by the animal. Afterwards, he should reload the other animal.When does the above apply? When the two people he encounters are both friends or both enemies. If, however, the one whose donkey must be reloaded is an enemy and the other is a friend, it is a mitzvah for the passerby to reload his enemy's donkey first, in order to subjugate his evil
…One might ask: How is it possible for one Jew to hate another? Is it not written Leviticus 19:17: "Do not hate your brother in your heart"? Our Sages explained that this is referring to a person who while alone sees a colleague violate a transgression and rebukes him, but the colleague did not cease transgressing. In such an instance, it is a mitzvah to hate the person until he repents and abandons his wickedness.Even if he did not repent yet, if one sees him in panic because of his cargo, it is a mitzvah to unload and reload with him, instead of leaving him inclined toward death, lest he tarry because of his money and be brought to danger. For the Torah showed concern for the lives of the Jewish people, both the wicked and the righteous, for they are attached to God and believe in the fundamentals of our faith. And Ezekiel 33:11 states: "Say to them, 'As I live,' says God, the Lord, 'Do I desire the death of a wicked man? I desire that the wicked return from his path and live.'Blessed be God who grants assistance.
Rambam holds that though it is a mitzvah to hate a sinner, there is still a requirement to rescue him when he is in danger. The travails upon the road might start with financial concerns but easily can turn into panic and dangerous behavior. Think of having a flat tire on a busy highway, or deserted road. Each scenario can spell danger when one inevitably becomes preoccupied with his possessions over personal safety. Thus, to assist in the load, is a form of preventing danger or death, and even a sinner merits such treatment.
A question arises in regard to shalach manos, whose obvious reason is to promote brotherhood and love. The verse (Esther 9:22) refers to “sending gifts to one’s fellow (re-eyhu).” The Hebrew word “Re-eyhu” implies a friend. So on the one hand, one might say that one cannot fulfill the mitzvah if sent to an enemy. On the other hand, one might derive from our Gemara that it is a special mitzvah to send to an enemy, “in order to overcome the evil inclination.” See Orchos Chaim (695:9) who discusses both sides of the issue.
(I must take a moment to share my amazement. The Torah scholars of our history were so clever and devoted to Torah study and observance. Who would have even thought of comparing our Gemara to the mitzvah of shalach manos? Simply breathtaking!)
I will add one final thought. Even if the halacha favors giving shalach manos to an enemy, in this case, the Rambam will agree with Tosafos, that it only refers to an ordinary garden variety enemy. This is because it is only a mitzvah to overcome this hatred for a sinner when he is in physical danger as we saw above. However, a sinner is obviously not in any physical danger by not receiving shalach manos, thus there is no good rationale for promoting brotherhood. (Unless, of course, you believe that somehow this will encourage his return to observance.)