In his post what-esav-soneh-lyaakov-really-means Dov Bear quotes R. Shimon b. Yochai's (Rashbi) famous saying:
"R. Shimon b. Yochai said: "It is a known fact (halacha b'yaduah) that Esav hates Yaakov, but, his mercy was aroused at that moment and he kissed him with all of his heart."
Dovbear goes out of his way to attempt to prove that contrary to the common interpretation, that Rashbi is talking of Esav as EDOM-ROME-CHRISTIANITY, Rashbi is actually just talking about good old physical Esav. In Dovbear's colorful words:
"The words Esav sonei le’Yaakov, therefore, should be understood as a straightforward, statement of fact about the nature of Yakov's relationship with his brother;"
This isn't the first time Dovbear has argued this. It was pointed out that the words "Halacha"(translated above as "known fact") would seem to point to a more metaphysical interpretation, rather then the mild, almost boring one that Dovbear is arguing for.
However DovBear can relax. He could have spared himself all the effort had he done his homework. Rabbi Benny Lou points out that in all the original manuscripts what is written is
"והלא בידוע שעשו שונא ליעקב"Literally "but it is known that Esav Hates Jacob". So how did the word "Halacha" enter the later versions of Rashbi's saying? In Hebrew you can abbreviate both the word "והלא" and the word והלכה as "והל'" . Some naughty scribe misinterpreted the abbreviation, and caused poor DobBear hours of needless worry.