Genesis 20:8

"Early the next morning Abimelek summoned all his officials, and when he told them all that had happened, they were very much afraid." NIV translation

Abimelek believed God and explained what had happened to his appointed leaders. They became afraid and, in this, we see that God has the power to work in the hearts everyone, even those who do not belong to Him. As the wisest man ever (Solomon) said, "the fear of the Lord is the beginning of knowledge". 

Genesis 20:9 & 10

"Then Abimelek called Abraham in and said, 'What have you done to us? How have I wronged you that you have brought such great guilt upon me and my kingdom? You have done to me things that should never be done.' And Abimelek asked Abraham, 'What was your reason for doing this?'" NIV translation

Abimelek asks Abraham why he did this to him. This is a reminder to us, as Christians, that our actions towards those who do not believe in Jesus are very important. Abraham was known to be a man of God and, yet, the king knew that his actions did not reflect that.  As children of God, we are to love other believers but we are also to love those who are perishing. Jesus said that people would know that we are His followers by the demonstration of our love.

Genesis 20:11 - 13

"Abraham replied, 'I said to myself, "There is surely no fear of God in this place and they will kill me because of my wife." Besides, she really is my sister, the daughter of my father though not of my mother; and she became my wife. And when God had me wander from my father's household, I said to her, "This is how you can show your love to me: Everywhere we go, say of me, 'He is my brother.'"'" NIV translation

Abraham begins his explanation with "I said to myself" and that is usually the place where the problem starts. It begins with fear and then grows from there. He did not go by what God had told him but by what he thought. It is the same for us when we fail to remember that what God says about something is what matters and not our thoughts or feelings. Then, he begins to minimize the offense by saying that what he had said was true but it just wasn't the entire truth. We are reminded that a half-truth is still a lie.