quoted The Sumerians by Samuel Noah Kramer

Samuel Noah Kramer: The Sumerians (Paperback, 1971, University Of Chicago Press) No rating

The Sumerians, the pragmatic and gifted people who preceded the Semites in the land first …

... near the very beginning of the document, one of these worthies addresses the other as follows:

You dolt, numbskull, school pest, you illiterate, you Sumerian ignoramus, your hand is terrible; it cannot even hold the stylus properly; it is unfit for writing and cannot take dictation. (And yet you say) you are a scribe like me.

To this the other worthy answers:

What do you mean I am not a scribe like you? When you write a document it makes no sense. When you write a letter it is illegible. You go to divide up an estate, but are unable to divide up the estate. For when you go to survey the field, you can't hold the measuring line. You can't hold a nail in your hand; you have no sense. You don't know how to arbitrate between contesting parties; you aggravate the struggle between brothers. You are one of the most incompetent of tablet writers. What are you fit for, can any one say?

The Sumerians by  (Page 241)

"you Sumerian ignoramus" is perhaps the greatest insult I have ever read, just an incredible document of diss tracks from antiquity