Unwilling to or refusing to forgive.

Unforgiveness means you are unwilling or refusing to make a deliberate decision to release the feeling of resentment or vengeance toward another person or group of people.

Unforgiveness is like taking poison but expecting someone else to die.

Unforgiveness is choosing to stay trapped in a jail cell of bitterness, serving time for someone else's crime. When boiled down to its essence, unforgiveness is hatred.

Matthew 6:15

But if ye forgive not men their trespasses, neither will your Father forgive your trespasses.

Matthew 18:30-35

He refused and went and put him in prison until he should pay the debt. When his fellow servants saw what had taken place, they were greatly distressed, and they went and reported to their master all that had taken place. Then his master summoned him and said to him, 'You wicked servant! I forgave you all that debt because you pleaded with me. And should not have had mercy on your fellow servant, as I had mercy on you?' And in anger his master delivered him to the jailers, until he should pay all his debt. So also my heavenly Father will do to every one of you, if you do not forgive your brother from your heart."

Matthew 6:14

For if ye forgive men their trespasses, your heavenly Father will also forgive you:

Mark 11:25-26

And when you stand praying, if you hold anything against anyone, forgive them, so that your Father in heaven may forgive you your sins."