May the God of Abraham, and the god of Nahor, the gods of their father, judge between us

Abraham is Jacob's grandfather. Nahor is Laban's grandfather. The father of Abraham and Nahor is Terah. Not all of them worshipped Yahweh.

the Fear of his father Isaac

Here the word "Fear" refers to Yahweh, who Isaac deeply respected and showed that respect by obeying him.