It's a little-known fact that I once took a graduate course in the Ancient Sumerian language. It was all part of my general interest in obscure and difficult languages, which continues unabated to this day.
I had to memorize archaic hieroglyphs, cuneiform logographs and vocabulary meanings, not to mention the bizarre Sumerian grammar (the agglutinative nature of which I am sometimes reminded of when I look at Korean).
I don't remember much of it – Sumerian is just not something one has much occasion to use.
Somehow I ran across a proverb that was allegedly Sumerian, the other day, and I wanted to find out if it was just an empty attribution or if it was really from Ancient Sumer. So I researched it a little bit. Apparently it's the real deal. I really wanted to find an image of the cuneiform inscription, but my googling skills have proven inadequate to that task. So here is the proverb and the transcription I found (at this website):
A heart never created hatred; speech created hatred.
Segment A: 1.105
71. šag4-ge šag4 ḫul gig nu-ub-tu-ud
72. dug4-ge šag4 ḫul gig ib2-tu-ud
Above right is an image of the archaic style (c. 3000 BC) I mostly focused on in my class but it's utterly unrelated to the quoted proverb. Below, likewise unrelated, is an image of the later, more refined style of the civilization at its height (c. 2000 BC – and note that the refined style below is just as likely to be Akkadian as Sumerian – the civilization was bilingual and used the same writing system for both languages, which were linguistically unrelated – actually, that's similar to the situation between Korean and Chinese in the pre-modern era).