ועַתָה לְכָה נִכְְרתָה בְִרית אֲנִי וָאָתָה
So now, come, let us form a covenant, you and I. (Bereishis 31:44)
There are two types of covenants. In one type, the two parties agree to pursue a common goal and a shared destiny. There will be interaction between their respective cultures and there would therefore be no hesitancy to intermarry with one another. In the second type, the two parties have no interest in pursuing a common goal. The agreement consists merely as a non-aggression pact, a pledge to respect each other’s independence.
Jacob agreed to establish a covenant with Laban, but the two had opposing visions of the type of covenant that was being formed. So Jacob took a stone and set it up [as] a monument: Jacob took a single stone, since for Jacob, the symbol of the covenant is a single stone which forms a barrier between his family and Laban’s. Yet, Jacob said to his kinsmen, “Gather stones” (verse 46). According to Nachmanides, Jacob was addressing
himself here to Laban’s sons. Jacob understood that for Laban and his family, the symbol of this covenant was the gathering of many stones, of the merging of different cultures and values.
Laban then states: May the God of Abraham and the god of Nahor judge between us, the god of their father. Abraham in his youth was an idolater just as Nahor was—both were taught to worship the god of their father, Terah [note: according to the Rav’s interpretation, the “god” of Abraham should not be capitalized]. Laban invoked this god as witness to the covenant. Jacob, therefore, did not include Abraham in his own oath: And Jacob swore by the Fear of his father Isaac. Jacob’s covenant conformed exclusively with the guidelines set by the God whom Isaac served his entire life.
And Jacob slaughtered a slaughtering on the mountain—in preparing the feast, Jacob prepared the animal in accordance with the laws of shechitah, of ritual slaughter. The laws of kashrus remind us that there should be no social interaction with idolaters, thus repudiating Laban’s interpretation of the covenant. Had Jacob adopted this interpretation, such a meal would have terminated Kedushas Yisrael, the holiness and uniqueness of the Jewish people. (Vayaged Yosef Hagadah, p. 22)
In my copy of the source, Vayaged Yosef Hagadah, it was on pages 43/44.