The Torah pays tribute to our matriarch Sarah at the end of her life:
And the years of the life of Sarah were one hundred years and twenty years and seven years; the years of the life of Sarah. And Sarah died in Kiryat Arba, which is Chevron, in the land of Canaan. And Avraham came to eulogize Sarah and to cry for her (Bereishit 23:1-2).
Here, Sarah’s name is mentioned specifically four times.

However, as soon as Avraham completes this stage of his mourning, and begins negotiations with the Hittite “local council” to purchase the cave of Machpelah from Efron, Sarah’s name ceases to be mentioned. Instead, every reference to her uses the impersonal noun MEIT, “dead”:
And Avraham arose from before his dead and he spoke to the children of Cheit, saying “. . . and let me bury my dead from before me.”
And the children of Cheit answered Avraham “. . . In the choicest of our graves bury your dead; not one of us would withhold his grave from you to bury your dead. . . .”
And he spoke with them, saying, “If it is your desire to bury my dead from before me . . .”
And Efron the Hittite answered Avraham “ . . . bury your dead.” ...
And he spoke to Efron, “ . . . and I will bury my dead there.” . . .
And Efron answered Avraham, saying to him, “. . . and your dead, bury” (vs. 3-15).
In every statement throughout the parley, reference is made to Avraham’s wife. Yet, eight times, Sarah is not referred to as “Sarah,” nor even “wife,” but only “dead.”

Of course, this highlights the fact that only the body dies. The soul, Sarah’s true essence, is eternal. This is implied in Ibn Ezra’s comment on verse 3:
before his dead: A reference to the body.

However, the closing section of this passage — after Avraham weighs out the four hundred shekels of silver in the presence of all the inhabitants of the city to purchase the cave and the surrounding field — poses a problem:
And afterwards Avraham buried Sarah his wife in the cave of the field of Machpelah before Mamre, which is Chevron, in the land of Canaan. And the field, as well as the cave in it, became established for Avraham as a burial plot, from the children of Cheit (vs.19-20).

If it is only the body that is buried, why is Sarah mentioned once again by name, including the rather tender appellation “his wife,” at the time of her burial?

A number of commentaries take note of the fact that verses 19-20 say the cave and field of Machpelah “became established for Avraham as a burial plot” after having said the same idea in verses 17-18. Ramban says the Torah wishes to emphasize that this became a legitimate and universally recognized (from the children of Cheit) possession of Avraham and his family. Moreover, it is, without question, “in the land of Canaan,” and not in the land of the Pelishtim, where Avraham lived heretofore (see Bereishit 21:34). Malbim adds that at first Machpelah became known as the family’s burial place, and then “the field” was designated as burial grounds, not to be used for planting.

As a result of this purchase, Avraham had an uncontested holding in the land of Israel, fulfilling Hashem’s many promises to give him the land.

And yet, Avraham realized that Hashem’s promise did not come easily. Our Sages (Sanhedrin 111a; Bava Batra 16a) explain that this episode is considered one of Avraham’s trials, demonstrating his outstanding steadfastness. Says Hashem:
I said to Avraham, “Arise, walk about in the land, along its length and breadth, for to you will I give it” (Bereishit 13:17). Nevertheless, when Avraham sought a place to bury Sarah he did not find one until he paid four hundred shekels of silver, yet he did not suspect My integrity.
Maharsha explains (on Bava Batra 100a) furthermore, that based on this same verse, when Avraham traverses the land he is laying claim to it, thus making it easier for his descendants to possess it. They will be inheritors of Avraham, not conquerors.

Out of all Hashem’s promises to Avraham, “Arise, walk about in the land” posed the greatest challenge: While others might refer to Avraham’s descendants, this verse enables Avraham himself to lay claim to the land by walking through it. The challenge to Avraham’s loyalty, therefore, is that he must pay so dearly for land that is already his! Or, rather, it should have been his. However, when he pays the price of the cave and field of Machpelah in the presence of the Hittites, the potential of “Arise, walk about in the land” is realized.

Sarah has been Avraham’s lifelong partner in teaching the world about Hashem:
“Avraham would convert the men and Sarah would convert the women” (Bereishit Rabbah 39:14).
As the mother of Yitzchak, she is Avraham’s partner in beginning the creation of the nation of Israel, thus fulfilling Hashem’s promise
And I will make you into a great nation (Bereishit 12:2).

Now, at the time of the acquisition of the cave of Machpelah, Sarah is again Avraham’s partner in realizing another of Hashem’s promises:
Arise, walk about in the land, along its length and breadth, for to you will I give it.

This is the meaning of the Midrash (Tanchuma Chayei Sarah 4) that sees in Eshet Chayil (Mishlei 31:10-31) a précis of Sarah’s life. On the verse (16):
She plans a field and acquires it the Midrash says:
She planned and acquired the field of Machpelah and she was buried there, as it says, “And afterwards Avraham buried Sarah.”

In fulfilling Hashem’s promise, Sarah can be called — even after death — by name, as well as Avraham’s wife. Her soul, her values, live on. It is through the union of Avraham and Sarah that the land of Israel becomes the rightful possession of the people of Israel.