Genesis 14:13

14:13 A fugitive came and told Abram the Hebrew. Now Abram was living by the oaks of Mamre the Amorite, the brother of Eshcol and Aner. (All these were allied by treaty with Abram.)

Genesis 18:1

Three Special Visitors

18:1 The Lord appeared to Abraham by the oaks of Mamre while he was sitting at the entrance to his tent during the hottest time of the day.