The two times Jules quotes Ezekiel 25:17, he quotes it slightly differently. Jules must have been reading one weird Bible, because the verse he quotes isn't like any version in print.
I would like to add that Quentin Tarantino stated in an interview that he knew it wasn't 100% correct, but they way he had written it enhanced the dramatic effect.
(Then where's the "slip-up", genius? It was done intentionally.)