The use of “a stiff neck” to denote obstinacy can be found in Deuteronomy 31:27, where Moses uses the term to describe the Levites to whom he entrusted his book of laws.
The adjective stiff-necked is used in the same sense in Acts 7:51, where Stephen is pleading his defense against blasphemy.
The German hartnackig and the Vulgate Latin dura cervice have the same significance, and both have the literal meaning “hard neck.”
All are derived from the Greek, from which much of the Bible has been translated, where the term is sklerotrhachelos, a compound from skleros, “hard,” and rhachis, “spine,” and the Greek is a direct translation of the Hebrew keshay oref.