Rash"i in Breishit 33:4 cites Sifrei, by stating:
הֲלָכָה הִיא בְּיָדוּעַ שֶׁעֵשָׂו שׂוֹנֵא לְיַעֲקֹב
It is a well-known halacha that Esav hates Ya'akov
How is this "well-known"? Based on what sources? If you look at the verse in Breishit, Esav kissed Jacob. Yes, I see Rashi's citation of Sifrei that implies that the kiss was sincere and it was only this time that he meant it. But, in a reading from the rest of the Torah, we don't find any situation were Esav attacked or was in any way hostile to Ya'akov or B'nai Yisra'el.
It seems that they were satisfied to be left alone. In parshat Chukat, we see that Moshe sent messengers requesting passage through their land, Edom, and they refused ans even set out against them "with a heavy force". However, this seems to be a defensive maneuver to discourage B'nai Yisra'el from passing through their land. I.e., they didn't actively bother B'nai Yisra'el in the desert or wage war against them.
So, how or why does R. Shimon bar Yochai say, "this is well-known"?