"Whoever loves discipline loves knowledge, but he who hates reproof is stupid."
The hardest sin to correct is in fact pride. A prideful man hates to be criticized. A prideful man does not believe what others say to him nor will he allow himself to be humbled by those he deems "inferior" as if their status could negate the truth. A prideful man is a foolish man who believes he is beyond reproach. Moreover, pride is subversive. A prideful man does not know he is prideful, nor can you tell him. Can you see why God cannot tolerate a haughty spirit? It is because they blaspheme the Holy Spirit else they would turn an be forgiven, and mark my words no man has ever been forgiven by God without first turning in humble repentance.
But to those who love discipline have been given the keys to the kingdom of heaven. Because they have humbled themselves and do not think of themselves any more highly than they ought, God has extended them divine grace and mercy in the form of discipline. That's right, discipline is a form of mercy when compared to God's other option for correction: death. God disciplines those that he loves as a father would discipline his Sons, so today if you hear God's voice do not harden your hearts, for God will exalt those in the lower places and humble those who are high.