Or HaChaim on Exodus 22:20/אור החיים על שמות כ״ב:כ׳

1 וגר לא תונה, "You shall not wrong a stranger, etc." Rashi says that if the Jew were to remind the stranger of his idolatrous past, he has to be prepared to be reminded by the stranger of his own unsalutary past. Ibn Ezra says that we must remember that we were once no better than the stranger. Nachmanides disagrees with both these interpretations and says that we must remember that G'd will respond to the oppressed just as He responds to our own outcries when warranted.

2Once we remind ourselves that the souls of the Jewish people are the very root of sanctity seeing that Abraham, Isaac, Jacob and their offspring were part of G'd's heritage, we can understand that Jews do not react to insults heaped upon them by the Gentiles. We do not even view such people as in the category of אדם. It is this attitude vis-a vis the Gentiles that provides the background for Jews belittling Gentiles, even those Gentiles who have ceased worshiping idols. As a result the Torah saw fit to tell us why we must not remind strangers of their idolatrous past. We are not to tell such people that they are rooted in the domain of the קליפות, i.e. that their intrinsic worth is inferior to ours. When the Torah reminds the Jewish people: "for you were strangers in the land of Egypt," this should be understood according to my comment on Genesis 46,3 and Exodus 20,2. I have demonstrated there that while the Jewish people resided in Egypt their own souls were mired deeply in the same moral morass that the souls of the Egyptians found themselves in.