Why Did Avraham Call Sara His Sister To Avimelech?

In this week's parsha after G-D destroys Sdom but before the Akeida, we have the incident where Avraham and Sarah go to the land of Avimelech. There are some similarities here to the happenstance of when Avraham and Sarah went to Egypt, but by in large there are differences. First off, why would Avraham tell everyone that Sara is his sister here? The Ramban points out that by Egypt Avraham had to tell everyone Sarah was his sister because it was a very corrupt society, but by Avimelech's kingdom there was justness and fairness like we see from how Avimelech treats Avraham after this incident and invites him to stay in his land. This is in contrast to Egypt where Avraham was kicked out once they found out Sara was his wife. Also, the Ramban points out that even if Avraham was afraid that Avimelech would steal his wife, she was now almost a hundred years old so how could Avimelech be interested in her?


I can't find any meforshim that explain this first question, but I would like to incorporate one of my own ideas to answer this question. The Ramban says that the only reason that Avraham decided to tell Avimelech that Sarah was his sister was because Avraham was worried that Avimelech was like Pharo. It is Interesting that Avraham would not be dan likaf zechus, give Avimelech the benefit of the doubt. Maybe we can all learn a valuable lesson from this incident. Avraham knew that Pharo, a powerful man, abused his power and therefore Avraham had to protect himself from being killed. This is why Sara went along with Avraham's plan and told everyone she was his sister. However, over by Avimelech we see that Avraham was telling people that Sarah was his sister and Sara would not be the one to say it. Maybe, just maybe, this can teach us that we should not judge all people that are in the same position in the same way. True Pharo abused his power, but Avimelech was a righteous king (Ramban's words not mine). The idea of giving people the benefit of the doubt seems important and very necessary over here since Avimelech was almost killed because it was not given. This could be why Sara would not initially tell anyone that she was Avraham's sister and it was Avraham that had to say that she was his sister.

The answer to Sara's desirability can be answered in one of two ways. One is that just like Rashi says in the beginning of parshas Chayei Sara that when she was a hundred she was as beautiful as twenty so we see that her beauty never waned. Or you could say that since Avraham was a powerful man and rich, by Avimelech stealing his wife it would have been a power play on Avimelech's part to show his superiority. If we look at the second possibility then, for Avraham, his concern is very legitimate, but if the beauty that avimelech desired was superficial then we have our previous question.