Genesis 23:9

that he sell me his double cave which is built in the side of his field, for the full price in silver let him give it me among you, for an inheritance of sepulture.

THAT HE MAY GIVE ME. The intent of this is “that he may give it to me in such a way that I will consider it as a gift (even) if I will buy it from him for its full value.” It is for this reason that Abraham did not mention the word “selling.” A similar usage is found in the verse, Thou shalt sell me food for money, that I may eat; and give me water for money, that I may drink, meaning “for the water which is usually given as a gift I will give money.” It may be that such is the ordinary usage of the language to mention “giving” when describing sales transactions.

THE CAVE OF MACHPELAH. Rashi comments: “It had a lower and an upper cave. Another explanation [of why it was called Machpelah — the root of which is keiphel (double)] — is that it was ‘doubled’ on account of the four couples who were buried there: Adam and Eve, Abraham and Sarah, Isaac and Rebekah, Jacob and Leah”. But this is incorrect since Scripture states, the field of Ephron which was in Machpelah. Thus we see that it is the name of the place in which the field was located, and there is no need to search for a reason for the names of places.
In Bereshith Rabbah, the Sages have said: “The Holy One, blessed be He, bent double the stature of the first man and He buried him there.” In their opinion, this entire place was always called Machpelah though the people did not know the reason for it for Ephron sold him everything for the price of the field unaware that there was a grave in it. Abraham, on the other hand, desired only that he should sell him the cave which was in the end of the field, and the field might be retained by Ephron. But Ephron by way of good conduct or trickery, [possibly hoping to receive a higher price for the larger transaction], said that he would give him the field and the cave which was in it since it would be unbecoming for such an honorable person to own the cave as a possession for a burial-place while the field belonged to another. Abraham rejoiced at this suggestion, and he purchased it in its entirety for the price that Ephron mentioned.

מערת המכפלה, any depression in the surface of the earth is called מכפלה, as the ככר הירדן, refers to the entire Jordan valley (13,10). This is substantiated by the Torah describing Efron’s field as being located in מכפלה in verse 18 of our chapter.

מערת המכפלה, a place known as machpela.

Compare verse 17 ויקם שדה עפרון אשר במכפלה אשר בקצה שדהו, “Efron’s field which is situated in machpela at the edge of his field, stood, etc.” The details provided by the Torah are intended to prove to us, the reader, that by selling the cave to Avraham Efron did not suffer any loss of face, he had no reason to feel embarrassed about what he had done.

בכסף מלא, I do not want that he grant me a reduction from its real worth as a gesture to you.

בתוככם, in the presence of all of you. I do not ask for time to come up with the payment but am willing to pay cash at once. Compare verse 16 where Avraham does in fact pay cash immediately.

לאחוזת קבר, Avraham wanted complete freedom to do what he wanted to in the property once he had acquired it. This is the privilege granted to anyone owning an ancestral heritage. Avraham wanted it understood that as a result of the sale Efron would not be able to dictate to him how close to his own property Sarah or other members of his family could be buried.

ויתן לי את מערת, he did not ask anything from Efron other than the cave, not the field in which it was situated.

המכפלה, the word is a noun describing a subordinate function. If it were an adjective the word מערת should have had the prefix ה. Our sages disagree concerning the meaning of the word מכפלה. Some think that it describes a cave above another cave, (root כפל, double) others claim it means a cave within another cave. Alternately, the word describes this particular location, i.e. that the whole cave was known as the “cave machpelah” on account of the dual cave contained in that field; this is also why the field itself was considered as almost subordinate to the cave in question.

כסף מלא, each coin would be of full weight, like a brand new coin which had not lost some of its original weight through being in circulation. The Torah makes this clear by adding the words עובר לסוחר, acceptable by any merchant.