John Gill Commentary Genesis 23:20

"And the field, and the cave that is therein, were made sure unto Abraham for a possession of a burying-place by the children of Heth." — Genesis 23:20 (ASV)

And the field, and the cave that is therein, was made sure to
Abraham for a possession of a buryingplace, by the sons of Heth
] Who were witnesses of the transaction between Abraham and Ephron; and this was further made sure by Sarah's being buried in it, which was taking possession of it, for the use for which it was bought; and was a pledge and earnest of the future possession of the land of Canaan by the seed of Abraham: this was the first piece of ground in it possessed by Abraham and his seed; and it being called the possession of a buryingplace, shows that there is no contradiction between this and what Stephen says, (Acts 7:5) ; he had a possession to bury in, but not to live upon; not any ground of his own to till and sow, or build upon.