Genesis 20:6 (KJV)

And Abraham journeyed from thence toward the south country, and dwelled between Kadesh and Shur, and sojourned in Gerar.

And Abraham said of Sarah his wife, She is my sister: and Abimelech king of Gerar sent, and took Sarah.

But God came to Abimelech in a dream by night, and said to him, Behold, thou art but a dead man, for the woman which thou hast taken; for she is a man's wife.

But Abimelech had not come near her: and he said, LORD, wilt thou slay also a righteous nation?

Said he not unto me, She is my sister? and she, even she herself said, He is my brother: in the integrity of my heart and innocency of my hands have I done this.

Now therefore restore the man his wife; for he is a prophet, and he shall pray for thee, and thou shalt live: and if thou restore her not, know thou that thou shalt surely die, thou, and all that are thine.

Therefore Abimelech rose early in the morning, and called all his servants, and told all these things in their ears: and the men were sore afraid.

Then Abimelech called Abraham, and said unto him, What hast thou done unto us? and what have I offended thee, that thou hast brought on me and on my kingdom a great sin? thou hast done deeds unto me that ought not to be done.

And Abimelech said unto Abraham, What sawest thou, that thou hast done this thing?

And Abraham said, Because I thought, Surely the fear of God is not in this place; and they will slay me for my wife's sake.