Genesis 49:30
It is the cave in the field of Machpelah, near Mamre in the land of Canaan, which Abraham bought for a burial plot from Ephron the Hittite.
Genesis 23:8-9
Then he said to them, "If you agree that I may bury my dead, then hear me out. Ask Ephron the son of Zohar
Genesis 23:16-18
So Abraham agreed to Ephron's price and weighed out for him the price that Ephron had quoted in the hearing of the sons of Heth -- 400 pieces of silver, according to the standard measurement at the time.
Genesis 23:20
So Abraham secured the field and the cave that was in it as a burial site from the sons of Heth.