Why not interpret consistently the way the age at death is expressed?

Question

The Torah says:

וַיִּהְיוּ֙ חַיֵּ֣י שָׂרָ֔ה מֵאָ֥ה שָׁנָ֛ה וְעֶשְׂרִ֥ים שָׁנָ֖ה וְשֶׁ֣בַע שָׁנִ֑ים שְׁנֵ֖י חַיֵּ֥י שָׂרָֽה׃ Sarah’s lifetime came to one hundred years and twenty years and seven years -- that was the span of her life. [Genesis 23:1]

Why not just say “one-hundred-twenty-seven years”? The Midrash explains:

When she was 20 she was as beautiful as when she was 7; and at 100 she was as sinless as a woman of 20, which is the age below which Heaven does not punish for sin. [Gen. R. 58:1]

But, as Ramban notes, the same language was used when Abraham [Gen. 25:7] and Ishmael [Gen. 25:17] died, and nobody interpreted it that way (except for Rashi on Abraham, with no source).

So why isn't this language interpreted consistently?

Edit: I am not asking why Ishmael gets a pass, but why the same expression is not explained consistently.

Answer 1

Rav Hirsch actually compares the usage at the death of Avraham with the usage at the death of Sarah He states that the two lived life fully with every day significant ימי שני חיי. On the other hand Yishmael lived his life שני חיי as a group of years. Indeed Rashi does give the same explanation for Avraham as he did Sarah.

Chayei Sarah 25:7 Rashi

one hundred years and seventy years and five years: When he was one hundred years old, he was as one who is seventy years old, and when he was seventy years old, he was as one who is five years old, without sin.

Rav Hirsch says:

ימי שני חיי etc., see above Ch. XXIII,1. Abraham too lived days and years, every day full of importance and all together one individual wholeand every period of life completely fulfilling its own significance. And yet all this were only days and years of the real life of Abraham which extended beyond the span of his earthly stay. It is peculiar that in Hebrew, large numbers of things areput in the singular, small ones in the plural. With years it is the same as with all large numbers. He who has a million pounds does not count single ones, who has only a little, every penny.

Answer 2

The Ramban explains that he is ONLY arguing with Rashi on how to make the Drasha. But he agrees with the Drasha.

The Ramban states that

שנה שנה ושנים דרך הלשון הוא. ...לא דרשו כן אלא מיתור הלשון, שחזר ואמר: שני חיי שרא

Year, year years is normal for language... the Rabbis expounded the fact that the end of the verse repeats "The years of Sarah"

The Ramban even brings the proof to his reasoning that they don't make this drasha for Avraham, and that is because there it does NOT repeat these last few words.

How beautiful the Ramban is. It is possible that Rashi agreed and only meant that since it repeats "shnei chaya sarah" at the end, why did it ALSO include shana multiple times, it could have read 127 shnei chayei sarah. So Rashi darshans the other part. What beautiful commentators. Like Gold! Similarly by Avraham there is a repition of Chai there but at the beginning so darshans like Sarah but not Yishmael who does not have anything extra. So Rashi darshans similary by Avraham but not Yishmael. Just my 2 cents.