1)
Why did Avraham prostrate himself before "Am ha'Aretz"?
1.
Seforno: As a mark of thanks, as if it was because of them that Efron was willing to enter into an agreement with him.
2.
Ha'Emek Davar: He was thankful to Am ha'Aretz for helping persuade Efron to sell. He was not thankful to Bnei Ches, for he understood their guile (to make him pay an exorbitant amount).
