BAM 27 - Returning only a Jew's lost objects

How do we understand the fact that the Torah only obligates us to return the lost object of a Jew?

Another place we have this question is in regard to the prohibition of taking interest on a loan, which is only forbidden when lending to a Jew, but not to a non-Jew. The question is, Why?

נראה לי בע"ה that the reason is as follows. (I believe the following is based on the Chofetz Chaim in Ahavas Chessed.) If we think about it, it really makes sense that one should charge interest to someone who is borrowing money. After all, they are receiving a benefit from my money, perhaps investing it in a lucrative business, while I sit at home without the money myself. There is certainly a monetary value to that, which I should be able to charge. Similarly, if someone loses an object, it should rightfully belong to the person who has found it, and not the one who lost it - as my 11th grade rebbe, Rav Yehoshua Kalish used to say, possession is ten-tenths of the law. If you have it, it's yours. If you lose it, it's gone!

The Torah, however, tells us a tremendous חידוש. This is that every Jew is considered your brother. A sibling identifies with his brother and would give him back an object he lost, despite the fact that he has every right to keep it. Similarly, a person who loves his brother would never charge him interest on a loan, but do it as a favor, completely altruistically. Hashem expects us to view every other Jew as our brother. This is a special relationship that Hashem desires to exist between the members of His chosen nation. These requirements are extra and beyond what is naturally called for. This is why they only apply to one's fellow Jew, and not to a non-Jew.

BK 92 - asking forgiveness

The Mishna says that one is not forgiven for the damage he has caused until he asks forgiveness from the one he caused damage to. This is proven from the passuk that states that Hashem commanded Avimelech to return Sarah to Avraham.

The question is, we don't seem to see anywhere in the verse that Hashem is telling Avimelech to ask for forgiveness, nor does it say that he asked for Avraham to pardon him, so what's the proof?

ונ"ל בע"ה that Hashem tells Avimelech to return Sarah to Avraham, and then says that Avraham will daven for Avimelech. The only way that Avraham would daven for him would be if Avraham feels positively toward him. Normally, when one causes an ill effect to his comrade, the compensation for the bad deed is not enough to placate him. Only once the person who has wronged his friend acknowledges his misdeed will the relationship return to its previous state. Thus the implication is that Avimelech is to get back on good terms with Avraham so they will be at the point where Avraham will daven for him.

This would also seem to be the understanding of the second passuk brought, where Avraham indeed davens for Avimelech. Here again we could ask how this proves that Avraham forgave Avimelech and therefore proves that one who has been damaged would also have an obligation to forgive the one who caused the damage? The answer be'H would be as we said, that from the fact that we see that Avraham davened, and he did so in such a way that indeed his tefilos were answered, this shows that he prayed in a fashion that was absolutely sincere and complete. This would only be possible if Avraham had completely forgiven Avimelech for his wrongdoing.