me'et benei-Chet - by the sons of Chet

The reason the Torah again stresses me'et benei Chet, as if the sellers had been a whole group of people instead of merely 'Efron is of crucial importance.  The Torah wants to forestall anyone ever raising any objection against this sale.  This is why the Torah repeats the story of the acquisition of this piece of property again at the end of Sefer Bereishit (49:32) prior to Yaakov being buried there.  The Torah speaks about this transaction no fewer than eight times in this portion, and twice more at a later date, making a total of ten references to what should be viewed as a simple transaction. 

Sadly, anyone living in our times realizes that all this was not enough to safeguard our claim to make it universally recognized.  Our prescient Sages in Bereishit Rabbah 58:8 have already foreseen such spurious counterclaims when they wrote: "how much ink has been spilled, how many styluses have been broken merely in order to write the words benei Chet (the Chittim).  Ten times did the Torah repeat its reference to the Chittim.  The Torah did so in order that anyone who acknowledges our title to the Cave of Machpelah be considered as if he had observed the Ten Commandments."  We find similarly excessive sounding verbiage in 1Divrei HaYamim 24 where David's purchase of the threshing ground of Arnon the Yevusi is described by Ezra HaSofer.  The word Arnon appears no few than then times in that report!

One of the moral lessons to be derived from our chapter is that even if man may conquer the whole of the inhabited part of the earth during his lifetime, in the end, when it is time to be buried, all he will own are the four cubits where he has been laid to rest. 

Avraham had been given the entire earth as a gift from G-d and what he had acquired by paying for it was only the Cave of Machpelah in the "city of four, i.e. in Chevron." 

Even though the Yisraelim conquered the whole of the land of Kenaan by the sword, we find that three locations in that country are distinguished especially.  This was so because they had not been acquired by force of arms but by legal tender, the previous owners having willingly forfeited their claim to these properties.  They are Chevron, Mount Gerizim and Mount Eival, and Mount Moriyah.  The Torah has documented our claim to Chevron in this portion.  Mount Gerizim and Mount Eival were the mountains where G-d concluded a covenant with the Jewish people (the generation which had not been of age or hand not been born at the time of the Exodus).  This area had already been bought by Yaakov when the Torah reported in Bereishit 33:19 "Yaakov bought the piece of land..."  Mount Moriyah's purchase has been documented in 1Divrei HaYamim 21.