He who hardens his neck and refuses instruction after being often reproved (corrected, criticized), will suddenly be broken beyond repair. Proverbs 29:1 (Amplified Bible)
The NIV says whoever remains stiff-necked. Stiff-necked, hardens his neck means not willing to accept the yoke. Imagine livestock that are not willing to be harnessed, not willing to take the yoke. Ever try to bridle a horse who is unwilling or stubborn- or try to put a halter on a young horse who is afraid?