שמות פרק יא , ב דַּבֶׂר-נָּא בְאָּזְנֵי הָּעָּם וְיִשְאֲלוּ אִיש מֵאֵת רֵעֵהוּ
It is a well-known statement in the Talmud the word רעהו refers to a Jew and not to a non-Jew (like love your friend like yourself). However, in this verse it obviously refers to the Egyptians, non-Jews.
It is possible to say that this verse is prior to Matan Torah, and the Jews and non-Jews were similar at that time. Only with the giving of Torah and the Jews attachment to it, did the Jews obtain a level of holiness and become separated from the non-Jews (as we say in Havdalah). This would help us to understand why we say Shira (Hallel) regarding the miracle at the Yam Suf that occurred outside of Eretz Yisrael (we do not say Hallel on Purim, since that miracle occurred outside of Eretz Yisrael). However, since at the time of the miracle of the Yam Suf, the Land of Israel had not yet acquired its holiness (which occurred when the Jews inhabited the land, and performance of Mitzvos within the Land of Israel).
Please note that in places where the non-Jews keep their Mitzvos, then certainly these non-Jews are included in the concept of רעהו, as cited in many places that our leaders referred to non-Jews, as our brothers or as our friends.
