Obstinate
Proverbs regarding adamant, firm, fixed, headstrong, inflexible, obstinate, persistent, relentless, rigid, single-minded, steadfast, stubborn, unbending, unshakable, unyielding
A wicked person shows boldness with his face, but as for the upright, he discerns his ways. Prov. 21:29 (read whole chapter)
Blessed is the one who is always cautious, but whoever hardens his heart will fall into evil. Prov. 28:14 (read whole chapter)
The one who stiffens his neck after numerous rebukes will suddenly be destroyed without remedy. Prov. 29:1 (read whole chapter)