en_tn/gen/31/51.md

This pile is a witness, and the pillar is a witness

These piles of stones were to act as a remembrance and a boundary marker for Jacob and Laban regarding their peace agreement. They are spoken of as if they are human witnesses. (See: rc://en/ta/man/translate/figs-personification)

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.