Rebecca

Just like his father
Isaac says, about his wife
“She is my sister”

Such duplicity.
If they have great faith in G-d
What have they to fear?

How can we explain
Such actions from our “Avot”?
Well … they’re just human

I’ve quoted below the Torah verses that tell of these deceptions. You might also want to click here for an interesting article by Rabbi Dan Judson on the My Jewish Learning website that suggests we view these three stories in the context of a literary approach to understanding Torah.

Gen 12:11-13    As they approached Egypt, [Avram] said to his wife Sarai, ‘I realize that you are a good-looking woman.  When the Egyptians see you, they will assume that you are my wife and kill me, allowing you to live. If you would, say that you are my sister. They will then be good to me for your sake, and through your efforts, my life will be spared.’

Gen 20:1-2   Abraham migrated from there to the land of the Negev, and he settled between Kadesh and Shur. He would often visit Gerar. [There] he announced that his wife Sarah was his sister, and Abimelekh, king of Gerar, sent messengers and took Sarah.

Gen 26:6-7   Isaac thus settled in Gerar. When the local men asked about his wife, he told them that she was his sister. He was afraid to say that she was his wife. Rebecca was so good-looking that the local men could have killed him because of her.

Yitzchak’s wife Rivkah
Literally the answer
To a servant’s prayers

Asked:
24:12, 14 ‘O God, Lord of my master Abraham: Be with me today, and grant a favor to my master Abraham … If I say to a girl, ‘Tip over your jug and let me have a drink,’ and she replies, ‘Drink, and I will also water your camels,’ she will be the one whom You have designated for Your servant Isaac.”

And answered:
24:19 When he had finished drinking, she said, ‘Let me draw water for your camels, so they can [also] drink their fill.’