Leonardo da Vinci painted the fresco “The Last Supper” in a church in Milan. Two very interesting stories are associated with this painting.
At the time that Leonardo da Vinci painted “The Last Supper,” he had an enemy who was a fellow painter. da Vinci had had a bitter argument with this man and despised him. When da Vinci painted the face of Judas Iscariot at the table with Jesus, he used the face of his enemy so that it would be present for ages as the man who betrayed Jesus. He took delight while painting this picture in knowing that others would actually notice the face of his enemy on Judas.
As he worked on the faces of the other disciples, he often tried to paint the face of Jesus, but couldn’t make any progress. da Vinci felt frustrated and confused. In time he realized what was wrong. His hatred for the other painter was holding him back from finishing the face of Jesus. Only after making peace with his fellow painter and repainting the face of Judas was he able to paint the face of Jesus and complete his masterpiece.
One of the reasons we may have a hard time accepting the forgiveness of God is that we find it hard to forgive others. That’s why Jesus said, “If you forgive men when they sin against you, your heavenly Father will also forgive you” (Matt. 6:14,15). If you want your relationship with Jesus to be all that it should be, forgive your enemies and do all you can to demonstrate Christ’s love to them.
Hot Illustrations For Youth Talks Wayne Rice, Zonderzan, pp. 161-162.

A successful Irish boxer was converted and became a preacher. He happened to be in a new town setting up his evangelistic tent when a couple of tough thugs noticed what he was doing. Knowing nothing of his background, they made a few insulting remarks. The Irishman merely turned and looked at them. Pressing his luck, one of the bullies took a swing and struck a glancing blow on one side of the ex-boxer’s face. He shook it off and said nothing as he turned the other cheek. The fellow took another glancing blow on the other side. At that point the preacher swiftly took off his coat, rolled up his sleeves, and announced, “The Lord gave me not further instructions.” Whop!
The Tale Of The Tardy Oxcart Charles R. Swindoll, Word, p. 214.

We had attended a nativity program with our friends and their two sons, ages 4 and 6, and were impressed with the boys’ fascination at seeing the baby Jesus in a manger. The play was, indeed, realistic and convincing.
Later at their home the boys started arguing, and after ignoring repeated warnings to stop, their mother sent them to their rooms to ask forgiveness from Jesus for their disobedience. When the older boy rejoined us, his mother asked him if he had asked Jesus to forgive him. “No,” he replied, “I asked God because Jesus is too young to understand.”
Beth Gearhart, Billings, MT. Christian Reader, “Lite Fare.”

Everyone says forgiveness is a lovely idea, until they have something to forgive, as we had during the war. And then, to mention the subject at all is to be greeted with howls of anger.”
C.S. Lewis Mere Christianity

There is one eternal principal which will be valid as long as the world lasts. The principle is — Forgiveness is a costly thing. Human forgiveness is costly. A son or a daughter may go wrong; a father or a mother may forgive; but that forgiveness has brought tears … There was a price of a broken heart to pay. Divine forgiveness is costly. God is love, but God is holiness. God, least of all, can break the great moral laws on which the universe is built. Sin must have its punishment or the very structure of life disintegrates. And God alone can pay the terrible price that is necessary before men can be forgiven. Forgiveness is never a case of saying: “It’s all right; it doesn’t matter.” Forgiveness is the most costly thing in the world.
William Barclay in The Letter to Hebrews – quoted off the internet