Hardness of Heart means unyielding, stubborn, "stiffnecked" (v. 11). Those were the weaknesses that caused the failure of Laman and Lemuel. In the kingdom of God, obedience is the condition of success. When Saul tried to justify his disobedience by the magnitude of his sacrifices, Samuel replied, "Hath the Lord as great delight in burnt offerings and sacrifices, as in obeying the voice of the Lord? Behold to obey is better than sacrifice, and to hearken than the fat of rams. For rebellion is as the sin of witchcraft, and stubbornness is as iniquity and idolatry." 1 Stubbornness is contrasted to obedience to the voice of the Lord.