In Parshas Chayei Sarah (24:1), the Torah tells how Avraham was getting old and needed to marry off his son Yitzchok. In describing Avraham, it says: “Avraham was old, coming along in his days, and Hashem blessed Avraham with everything.” Why does the Torah use the double expression “he was old, coming along in his days” and not simply say he was “old?”
The Zohar explains (vol. I, 129a and 224a) that “days” is also a metaphor for the spiritual accomplishments created by Mitzvos that we perform every day.
The purpose of why Hashem creates time, and creates a new day every day, is to reveal Hashem in the world through the Torah and Mitzvos. Therefore, the inner meaning of a “day” is what is accomplished that day.
When it says that Avraham was “coming along in his days” it does not just mean he had physically lived through many days, but rather, that he took with him all the spiritual accomplishments that he created from serving Hashem each and every day of his life.
The Zohar describes these daily spiritual accomplishments as “garments.” This is because each Mitzvah creates a Divine revelation that clothes the soul of the person and allows him to perceive and experience the deep wisdom of Hashem’s Torah in the spiritual realm of Gan Eden. Without those “garments” for the soul created by the Mitzvos, the finite soul is unable to fully experience the (relatively) infinite revelation of Hashem in Gan Eden.
The verse is thus saying that when Avraham was old, he came and brought with him all the spiritual “garments” that he created from his daily Mitzvos.
The Alter Rebbe in this maamar will explain this teaching from the Zohar in connection with a teaching from Pirkei Avos: