Charles Ellicott Commentary Exodus 32:9

"And Jehovah said unto Moses, I have seen this people, and, behold, it is a stiffnecked people:" — Exodus 32:9 (ASV)

It is a stiff-necked people. —This phrase, afterwards so common (Exodus 33:3; Exodus 33:5; Exodus 34:5; Deuteronomy 9:6; Deuteronomy 9:13; Deuteronomy 10:16; 2 Chronicles 30:8; 2 Chronicles 36:13; Psalms 75:5; Jeremiah 17:23; Acts 7:51), occurs here for the first time. It is generally explained as “obstinate,” but rather means “perverse,” the metaphor being taken from the horse that stiffens his neck against the pull of the rein, and will not be guided by the rider. The Septuagint omits the verse, for no intelligible reason.