Our Gemara on Amud Aleph tells us a story about Hillel the elder who was confronted by the zealous students of Shammai on his way to bring an Olah sacrifice on Yom Tov. Now according to Hillel, one may bring an Olah sacrifice on Yom Tov, but according to Shammai at this point in the Gemara, one may only bring a Shelamim sacrifice. Unlike the Olah, a Sehlamim has meat that can be eaten and hence it is ochel nefesh, permitted food preparation on Yom Tov. Hillel, wanting to avoid an ugly quarrel, fibbed and claimed the animal was a Shelamim, when in fact it was not.

Rashi says that Hillel was unassuming and permitted himself to lie in order to maintain peace. Of course the famous source that it is permitted to lie in order to maintain shalom comes from a Rashi we all learned in grade school, based on a Midrash (Bava Metzia 87a). After the prediction that Sarah would be holding a son next year at this time, she incredulously states: 

⁦And Sarah laughed to herself, saying, “Now that I am withered, am I to have the smooth skin of youth — with my husband so old?” (Bereishis 18:12).

⁦Then the LORD said to Abraham, “Why did Sarah laugh, saying, ‘Shall I in truth bear a child, old as I am?’ (Ibid 13)

When God relays the story to Avraham, he leaves out the part about Avraham being old and only mentions Sarah’s reference to her own elderly state. From here we see that if God can omit something, and possibly alter what was said (see Daas Zekeinim Bereishis ibid for two opinions on this) for the sake of truth, surely then mere mortals should do so as well.

The Daas Zekeinim asks what was the actual insult in Sarah’s words? Was Hashem concerned that Avraham would feel insulted at being called old? Let us imagine Rav Moshe Feinstein or Rav Kanievsky in place of Avraham. Would they really find being called elderly insulting? Now the mussar schools would answer, “No, but in some fine, minute, dakey dakus manner, avraham would have felt a twinge of a twinge of some bad feeling. And the lesson is we must be careful of that.” 

If you find that kind of reasoning understandable, then go for it. Personally, I find it to be reductio ad absurdum. Either Avraham cared or he didn’t. Reducing it to a twinge of a feeling just sets up an avoidance of the age-old problem of what genuine, but petty emotions, can we fairly attribute to the saintly Biblical figures? Clearly, they were human beings, and therefore did have emotions and foibles on some level. On the other hand what that level was, and how we are to relate to it without disrespect, is not simple. I don’t think there’s an easy answer. This is why I find The Daas Zekeinim’s approach to be more reasonable. He doesn’t attempt to explain how Avraham could feel bad about being called elderly, and especially in a culture where elderly men were respected and admired, it really doesn’t make sense. Instead, he offers a completely different explanation: 

He says that Sarah’s main point in declaring that her husband was too old to father children was that he was “tochen v’eyno polet”, that is no longer was fertile in the sense that he was not ejaculating semen. Now this makes sense because it’s quite possible that she was more aware of those biological functions than he was in, that the woman might notice after intercourse what occurred or didn’t occur. And then we are not dealing necessarily with a petty ego thing, instead we are dealing with the emotional anguish of discovering that one is older and less capable than one believes. That is not vanity over feeling old, but distress over being disabled. After all, it is a biological fact that many elderly men can still father children. That Sarah was privy to a somewhat distressing fact about Avraham, was not something she would ordinarily share with him as it would cause him sadness for no redeeming reason. It was this matter that God deliberately held back from Avraham.

Ultimately, the lesson is the same. And that is, if there is something that is of no relevance and there’s nothing that can be done about it, it is better to hold back information and possibly even distort the truth to protect another person’s feelings.