Genesis 23:16-18

So Abraham listened to Ephron [and agreed to his terms]; and he weighed out for Ephron the [amount of] silver which he had named in the hearing of the Hittites: four hundred shekels of silver, according to the weights current among the merchants. So the field of Ephron in Machpelah, which was to the east of Mamre (Hebron)—the field and the cave which was in it, and all the trees that were in the field and in all its borders around it—were deeded over [legally] to Abraham as his possession in the presence of the Hittites, before all who were entering at the gate of his city.