And the life of Sarah was one hundred years, twenty years and seven years (Genesis 23:1)
At the age of 20 she was like age seven in beauty, and at the age of 100 she was like age 20 in piety.
(Rashi; Midrash Rabbah)
I am a stranger and a resident amongst you (23:4)
The Jew is a "resident" in the world, for the Torah instructs us not
escape the physical reality but to inhabit it and elevate it. At the same time, the
Jew feels himself a "stranger" in the material world -- his true home is
the world of spirituality, holiness and G-dliness from which his
soul has been exiled and to which it yearns to return.
Indeed, it is only because he remains a "stranger" that he can maintain
the spiritual vision and integrity required to reside
in the world and sanctify it as a "dwelling for G-d."
(The Lubavitcher Rebbe)