What does Genesis 20:13 mean?
Abraham continues his explanation to Abimelech about why he lied about Sarah being his sister. First, Abraham admitted he was afraid that someone would kill him to take Sarah. Next, he revealed that Sarah was, after all, his half-sister. Finally, he claims that telling this lie has been a strategy they have used ever since they began traveling away from the safety of their homeland. More specifically, Abraham says that he asked Sarah to participate in this lie as a kindness to him.As details appear, it becomes harder for us to sympathize with Abraham in this situation. He is admitting, here, that he has repeatedly asked Sarah to put herself in harm's way in order to save his own life. In addition, this is only the second time Scripture has mentioned him doing this when coming to a new place (Genesis 12:12–13). So, is Abraham lying about it being their normal routine? Or has it happened in other places, as well? We don't know.
This is the end of Abraham's explanation to Abimelech, as unsatisfying as it must have been.
Genesis 20:1–18 describes what happens when Abraham once again moves to a new place and insists on lying that Sarah is merely his sister and not his wife. Abimelech, the king of Gerar, takes Sarah as one of his wives. He is soon struck with an illness and visited in a dream with a warning from God that he will die if he doesn't return Sarah to Abraham and if Abraham doesn't pray for him. Sarah is returned untouched, Abraham prays, and all are healed.
Here, Abraham practically duplicates one of the oddest episodes in his earlier life. As he did with the Egyptians in Genesis chapter 12, Abraham moves through a new area and claims that Sarah is his sister. The king of Gerar, Abimelech, takes Sarah for one of his wives, but he is soon struck ill. God appears and tells Abimelech he will die for taking a married woman. Abimelech insists he did not know and has not slept with Sarah. The Lord says that if he returns her, and if Abraham prays for them, all will be healed.