Musar על בבא מציעא 64:16

The commandment requiring us to help the owner of an overloaded animal or human being (22,4) by unloading the excessive load is directed at the natural tendency to ignore the discomfort of our detractors. The Torah demands that we put aside such petty considerations and display empathy with the pain of such a human being. When the Torah phrases the action to be taken by using the words הקם תקים עמו, the emphasis is on the last word, i.e. what you do for the victim you are really doing for yourself. By having demonstrated this kind of empathy you may feel confident that, should the occasion arise, you too will become the beneficiary of someone else's empathy. The Talmud Baba Metzia 31 says that given a choice of helping one's friend unload an overburdened animal and helping an enemy load his beast, you must give preference to loading the enemy's beast; such an act helps restore harmonious relations between him and you (cf. Exodus 23,5).