Verse 6 summarizes what is said in verse 4-5, and adds the final comment: you are a stubborn people. The Hebrew phrase rendered stubborn is “stiff-necked,” used always of people (see 9.13; 10.16; 31.27; also Acts 7.51). It indicates their unwillingness to obey God’s commands. In some languages this will be rendered with figurative expressions; for example, “hard-necked,” “hard-hearted,” or “bone-hearted.”

Quoted with permission from Bratcher, Robert G. and Hatton, Howard A. A Handbook on Deuteronomy. (UBS Helps for Translators). New York: UBS, 2000. For this and other handbooks for translators see here .