The request Abimelech makes of Isaac is almost humble. "Lest thou do us evil. Forasmuch as we have not come nigh thee for evil, and as we have acted with thee only for good, and have indeed sent thee away in peace; thou art now blessed of the Lord" (Genesis 26:29).
The Targum Pseudo-Jonathan lets the king's logic stand bare. We did not harm you. We sent you away peacefully. Now you are visibly blessed. Please — do not use your blessing against us.
The fear of the righteous man's power
This is a distinctive feature of Jewish storytelling. The patriarchs do not carry armies; they carry blessing. And blessing, the rabbis taught, is a real force in the world. Abimelech knows what he saw when Isaac left: wells drying, trees failing. The king is now worried about what Isaac, if he wanted to, could call down from Heaven.
The Talmud in Chullin teaches that kol tzaddik gozer v'ha-Kadosh Baruch Hu mekayem — a righteous person decrees, and the Holy One, blessed be He, fulfills. Abimelech is implicitly acknowledging this. He is signing a treaty not with a warlord but with a man whose prayers have teeth.
The takeaway
Pseudo-Jonathan preserves a moment that should shape how we think about power. Abimelech wants peace not because he fears Isaac's sword but because he has seen Isaac's God. The strongest protection a Jew has ever carried is not armor. It is the weight of a promise made in Beersheba on a dark night. And the nations of the world, the Targum teaches, often know this before we do.