וַיֹּאמְר֗וּ רָא֣וֹ רָאִינוּ֮ כִּֽי־הָיָ֣ה יְהוָ֣ה ׀ עִמָּךְ֒ וַנֹּ֗אמֶר תְּהִ֨י נָ֥א אָלָ֛ה בֵּינוֹתֵ֖ינוּ בֵּינֵ֣ינוּ וּבֵינֶ֑ךָ וְנִכְרְתָ֥ה בְרִ֖ית עִמָּֽךְ׃
Y ellos respondieron: Hemos visto que SEÑOR es contigo; y dijimos: Haya ahora juramento entre nosotros, entre nosotros y ti, y haremos alianza contigo:
Rashi on Genesis
ראו ראינו WE SAW PLAINLY (literally, seeing we have seen) — We saw it in the case of your father and we see it in the case of yourself (Genesis Rabbah 64:10).
Rashbam on Genesis
תהי נא אלה, which is בינותינו, between your father and me should remain in force also between בינינו, ובינך, between you and me. This had been part of the condition of that pact that neither Avraham’s children nor grandchildren were allowed to renege on a promise he had made on their behalf. (21,23)
Sforno on Genesis
כי היה ה' עמך, we do not want to make a deal with you because we are afraid of you, but because G’d is on your side.