Mamrei - The Faithful Ally
Together with his brothers Eshkol and Aneir, Mamrei the Emorite was a faithful ally of the Patriarch Avraham. It was in the plains of Mamrei that Avraham established his home shortly after arriving in Eretz Yisrael and where he built an altar to G-d in gratitude for the Heavenly gift of all of the land.
Mamrei was also the one who encouraged Avraham to go through with his circumcision in public fashion without fear from his enemies. In recognition of this, G-d chose the Plains of Mamrei as the site for appearing to Avraham following his circumcision.