I'm looking for the place in Mishneh Torah, I believe in Hilchot Avoda Zara V'Chukot Goyim, where it lists the prohibition on stealing ( genivah ) from a non-Jew, but I can't seem find it.
It appears in Mishneh Torah, Sefer Nezikin, Hilchot Gezeilah v'Aveidah, Chapter 1.
My rough translation: Anyone who steals money or something that is worth more than a perutah has transgressed the negative commandment of: "Do not steal". And one does not receive lashes because of this since it is a transgression that one may pay back, since the Torah has obligated (the thief) to pay (back the money or stolen property). And this applies equally to one who steals the money of a Jew, or one who steals the money of an idolatrous gentile, or to one who steals the money of an adult or of a child.
In the vilna edition this appears in Halacha 2:
My rough translation: "It is forbidden from the Torah to steal, and one may not even steal from a non-Jew. And if one steals, one must return (the stolen property)."
As Robert points out below, the above translations are not completely accurate, since they all translate the verbs גונב, גוזל, and עושק as "to steal", when really each one refers to a different manner of theft (the differences are discussed in other later halachot in Chapter 1).
The Magid Mishnah cites the primary source for this (among others) as being in Bava Kama 113b.
Any suggestions on improving my translation are welcome.