Genesis 14:5-13

And there came one that had escaped, and told Abram the Hebrew; for he dwelt in the plain of Mamre the Amorite, brother of Eshcol, and brother of Aner: and these were confederate with Abram.

Abram might be called the Hebrew, either from Eber, his ancestory as above, or else from his having passed the Euphrates, when he became a passenger, or pilgrim, in the land of Canaan.