Sarah’s Lifetime and the Qualities of Age and Youth

Sarah’s lifetime was one hundred years, twenty years, and seven years; the years of Sarah’s life. (23:1) Rashi: 20 years as 100 years

There are advantages of the elder years, such as: Yishuv HaDaas (calmness of the mind), the decreasing of pursuing lust, etc. to the contrary there are also advantages of the youth, such as Hislahavus (enthusiasm), energy, Zrizus (swiftness), etc. The Torah is telling us, that Soroh steadily fulfilled both qualities, those of elder, and those of youth. When she was twenty years old, she already had the qualities of a one-hundred-year-old, and when she was a hundred years old, she still attained the qualities of a twenty-year-old.

Der Torah Kvall - Bisheim Godol Echod