Genesis 12 has two parts.
God Called Abram (vs 1-9)
Sarai’s Beauty (vs 10-20)
God Called Abram
The Lord (to Abram): Get out of your country, and from your kindred, and from your father’s house to a land that I will show you. And I will make of you a great nation, and I will bless you, and make your name great; and you shall be a blessing. And I will bless them that bless you, and curse him that curses you: and in you shall all families of the earth be blessed.
So Abram departed, as the Lord had spoken to him; and Lot went with him: and Abram was 75 years old when he departed out of Haran.
Abram took Sarai/Sarah his wife, and Lot his brother’s son, and all their substance that they had gathered, and the souls that they had gotten in Haran; and they went forth to go into the land of Canaan; and into the land of Canaan they came.
And Abram passed through the land to the place of Shechem, to the plain of Moreh. And the Canaanite was then in the land.
The Lord appeared to Abram.
The Lord: I will give this land to your seed.
There Abram built an altar to the Lord.
Then Abram left there and went to a mountain on the east of Bethel, and pitched his tent, having Bethel on the west, and Ai on the east: and there he built an altar to the Lord, and called upon the name of the Lord.
Abram journeyed, going on still toward the south.
There was a grievous famine in the land. Abram went down into Egypt to stay temporarily there.
Abram (to Sarai his wife): You are a fair woman. When the Egyptians see you, they shall say, This is his wife. They will kill me, but they will save you alive. So, say you are my sister, that it may be well with me for your sake; and my soul shall live because of you.
When Abram was come into Egypt, the Egyptians beheld the woman that she was very fair.
The princes of Pharaoh also saw her and commended her before Pharaoh. Sarai was taken into Pharaoh’s house.
The Pharaoh entreated Abram well for her sake. He had sheep, and oxen, and he asses, and menservants, and maidservants, and she asses, and camels.
And the Lord plagued Pharaoh and his house with great plagues because of Sarai Abram’s wife.
Pharaoh (to Abram): What is this that you have done to me? Why didn’t you tell me that she was your wife? Why did you say, She is my sister? I might have taken her to me to wife: now therefore take your wife and go your way.
Pharaoh commanded his men concerning Abram. They sent Abram away, and his wife and all that he had.
Some would say that Sarai lied. But she actually was Abram’s sister (his half-sister).
Genesis 20:12 Abram says, Indeed Sarai is my sister; she is the daughter of my father, but not the daughter of my mother; and she became my wife.