Genesis 12

Abraham telling the Egyptians that Sarah is his sister can be very confusing.

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“To kill the husband in order to possess himself of his wife seems to have been a common royal custom in those days. A papyrus tells of a Pharaoh who, acting on the advice of one of his princes, sent armed men to fetch a beautiful woman and make away with her husband. Another Pharaoh is promised by his priest on his tombstone, that even after death he will kill Palestinian sheiks and include their wives in his harem.” (Kasher, Encyclopedia of Biblical Interpretation, 2:128.)

Abraham could validly state that Sarah was his sister. In the Bible the Hebrew words brother and sister are often used for other blood relatives. (See Genesis 14:14 , in which Lot, Abraham’s nephew, is called “his brother.”) Because Abraham and Haran, Sarah’s father, were brothers, Sarah was Abraham’s niece and thus could be called sister . The accompanying pedigree chart shows this relationship.

Another ancient custom that might shed light on the relationship permitted a woman to be adopted as a man’s sister upon their marriage to give her greater legal and social status (see Encyclopaedia Judaica, s.v. “Sarah,” 14:866).

Even though Abraham was correct in calling her his sister, he did deceive the Egyptians. How can this action be justified? The answer is very simple. His action was justified because God told him to do it (see Abraham 2:22–25 ). The Prophet Joseph Smith taught the following:

“That which is wrong under one circumstance, may be, and often is, right under another.

“God said, ‘Thou shalt not kill;’ at another time He said, ‘Thou shalt utterly destroy.’ This is the principle on which the government of heaven is conducted—by revelation adapted to the circumstances in which the children of the kingdom are placed. Whatever God requires is right, no matter what it is, although we may not see the reason thereof till long after the events transpire.” ( Teachings, p. 256.)

Since God is perfect and does not do anything that is not right (see Deuteronomy 32:4 ; 1 Samuel 15:29 ; Alma 7:20 ; D&C 3:2 ), Abraham’s act was not wrong.

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A few thoughts:

Sarah must have been extremely beautiful
Wealth can do good things for those who are able to practice restraint and use it wisely. Maybe the Lord sent them into this situation so Abraham could build up his worldly possessions even further?
As it is phrased here the pharaoh actually sounds like a nice guy. He would not have killed Abraham to marry Sarah as Abraham feared he might.