“From Beersheba” – Rabbi Yudan and Rav Huna, Rabbi Yudan said: From the source [be’er] of the oath [shevua]. He [Jacob] said: So that Avimelekh will not stand over me and say: ‘Take an oath to me just as your grandfather took an oath to me,’ and I will delay the joy of my descendants for seven generations.7Abraham's oath caused a delay of seven generations. See Bereshit Rabba 54:4. Rav Huna said: [He departed] from the source of the birthright.
He [Jacob] said: ‘So that Esau will not stand over me, challenge the birthright, and say: This is how you deceived me and took my birthright.’ The result will be that I will lose that oath, as it is stated: “Take an oath to me this day” (Genesis 25:33). “From Beersheba” – Rabbi Berekhya said: From the source of the blessings. He [Jacob] said: ‘So that Esau would not stand over me and say to me: This is how you deceived me and took the blessings.’ The result will be that I will ruin all the toil that my mother toiled on my behalf.