And they (the Angels) said to him (Avraham), "Where is Sarah your wife?" And he said, Behold! She is in the tent."
There are two opinions in Gemara Babba Metziah (87A) why the malachim asked Avraham where Sarah was. The first opinion explains that the malachim (angles) asked where Sarah was simply because they did not know where she was, and the Torah wrote this to teach US that Sarah was very modest. Rav Yehudah in the name of Rav and some say Rav Yehudah said it in the name of Rebbi Yitzchak explains, that the malachim really did know that Sarah was in the tent, and they asked Avraham only so AVRAHAM would realize that Sarah was very modest, and like this they would strengthen the bond between them.(Maharsha)
Zera Shimshon asks on each of these two opinions.
According to the first opinion, Zera Shimshon asks, why did the Torah find it necessary to mention that Sarah was modest? Since we know that she was tremendously righteous, obviously she was also modest!
On Rav Yehudah in the name of Rav's opinion Zera Shimshon asks; in the beginning of Parshas Lech Lecha, after Avraham and Sarah left Eretz Yisroel because of a famine, when they came close to Mitzrayim, it is written; And Avraham said to his wife Sarah; I now know that you are a beautiful woman. Rashi comments that because they were so modest he never noticed her beauty until then, and it was only by chance that he noticed it at all. This being so, Zera Shimshon asks, why did the melachim have to tell Avraham that she was modest? Avraham already knew it!
Zera Shimshon answers the second question in light of the Gemara Shabbos (53B), "The Rabbis learnt: A certain man was once married to a woman with a stumped hand, yet he did not notice it until the day of her death. Rebbi Yosef observed: How modest this woman must have been, that her husband did not know this! R’ Chiya replied, for her it was natural; but how modest this man was, that he never examined his wife!"
From here we learn that a wife is not the only one who creates modesty between a couple. It could be the result of the combined effort of the husband and his wife.
According to this, the fact that Avraham did not recognize Sarah’s beauty all the years of their marriage is not a proof that Sarah was exceptionally modest. Avraham might have thought that it was the product of both of their behaviors. The malachim therefore told Avraham that the truth is that Sarah was very modest in her own right.
Regarding the first question, why did the Torah have to teach us that Sarah was modest since we know that she is very righteous, Zera Shimshon explains the main reason for a woman to be modest is to assist men, who have a very strong yetzer hora, not to sin.
On the possuk (18/5), "And I (Avraham) will take (for you) a little bread, and sustain your hearts...." Rashi points out that the words "your hearts" is written "libachem" with only one bais which implies only one heart and not "levavachem" with two "baisem" which implies two hearts. Rashi explains the reason for this is because angels have only one yetzer, the yetzer tov, and not two, the yetzer hora and the yetzer tov, like mortals have. Since Avraham is the one that said this, we can infer that he and Sarah knew that their guests were angels and not mortals.
According to this, concludes Zera Shimshon, the special modesty that Sarah had more than a regular righteous person was that even though there was no practical reason for Sarah to stay in the tent since the men outside were angels and not mortals and had no yetzer hora we see that she was intrinsically and exceptionally modest!
