The KJV translators did not follow the Masoretic vowel pointing which has the Cholem above the Vav, which renders the word as "שֹׁור" (oxen). The LXX has "ταῦρον" (bull) which agrees with the Masoretic rendering. The Dead Sea Scrolls have this portion in fragment 4QGene but is of no use to our current discussion because vowels do not appear in the Dead Sea Scrolls (though some English translations of the Dead Sea Scrolls might render the phrase as "hamstrung oxen").
The KJV translators saw the Vav as a Shureq, rendering the word as "שׁוּר" (wall). Agreeing with the KJV is the Vulgate, having "murum" (wall). It is generally believed that Jerome consulted Rabbinical sources for the Vulgate. The Targums of Onkelos and Jonathan Ben Uzziel also have "wall" at Genesis 49:6:
The Midrash of Genesis Rabbah renders the word as "שׁוּר" (wall) to get the phrase "rased a wall". The Midrashic interpretation is that Simeon and Levi destroyed the confidence (wall) of the Gentiles by deceiving them into converting only to kill them (Volume 2 of Midrash Rabbah, edited by Rabbi Dr. H. Freedman and Maurice Simon (London : Soncino, 1983), p. 953).
Therefore, there are very ancient Rabbinical sources supporting the KJV rendering that Jacob reprimanded Simeon and Levi for destroying the wall of Shechem rather than hurting oxen. If Genesis 49:6 is taken to be a summary of the massacre and looting of Shechem, it would not make sense to say that Simeon and Levi "hamstrung oxen". Genesis 34:27-29 says the sons of Jacob took the cattle, but does not say they injured them. From a common sense viewpoint, it would hardly make sense for the sons of Jacob to hurt the oxen which they sought to possess. It does make sense, however, for either a wall of the city or a home to have been destroyed during the massacre and looting.
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