Kim Kardashian really upset the executor of O.J. Simpson‘s estate … and, now he’s throwing low blows at her — insulting the reality star for failing the bar exam in California!

Here’s the deal … the fourth episode of the new “The Kardashians” season came out Thursday — and part of it focuses on Kardashian attempting to buy the Bible her dad, Robert Kardashian, wrote an inscription in and gave to O.J. Simpson shortly after Juice’s arrest.

The clip shows Kim talking to Ollie Ayling — a consultant she works with — about securing the tome … diving into the moment we published a story about Kim offering $15K to obtain it.

Kardashian says in the clip that was just an initial offer, and she would’ve even gone up to $30K because of how much the book would mean to her and Khloé Kardashian … to whom Kim says she planned to give the book.

Kim says, “I guess I had a little too much faith in humanity for a minute there.”

Well, the executor Malcolm LaVergne ain’t happy about Kim’s comment … telling us, “I like how she’s trying to frame the story as I’m trying to keep it from her. No wonder she can’t pass the bar. By the way, I’ve passed three. First time each. New York Texas and Nevada. I will give her credit for being richer than me. No denying that.”

Kim revealed last weekend that she didn’t pass her first attempt at the bar exam, though she was super confident she had … so, LaVergne’s pouring salt into the wound here.

It’s worth noting … the Kardashian Bible ultimately went for $80K — so Kim’s opening salvo was far too low. Plus, LaVergne has said the estate was under legal obligation to auction off the Bible and couldn’t pick and choose what to sell to private vendors.