There are plenty of books and journals with translated cuneiform texts. I suspect this is from one of them (and I suspect that Nebuchadnezzar didn’t write it or compose it himself. It’s probably not even from his time). If Durant doesn’t give the reference, you’ll just have to look for it.
Unfortunately, most of these books didn’t have big printings, and are often quite old. If there isn’t a major university or old city library near you, you might have a hard time locating it. One book that’s in a lot of libraries is Ancient Near East Texts Relating to the Old Testament.