Genesis 23:16-18

23:16 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.

23:17 So Abraham secured Ephron’s field in Machpelah, next to Mamre, including the field, the cave that was in it, and all the trees that were in the field and all around its border, 23:18 as his property in the presence of the sons of Heth before all who entered the gate of Ephron’s city.