Lamar Sally -- I Never Asked Sherri Shepherd To Stay Thin

Lamar Sally tells TMZ he did NOT want Sherri Shepherd to sign an amendment to their prenup ... despite the fact that TMZ has a copy of the amendment in question.

Lamar insists, "I did not want her to sign an amendment to our prenup." TMZ broke the story, at some point during the marriage, he presented Sherri with a document that required her, among other things, to say she would commit to staying thin. We're told she refused to sign it.

And we're told Sherri's current lawyer is in possession of the amendment in question.