And now, swear to me here by God that you will not deal falsely with me or with my son or with my grandson; according to the kindness that I have done with you, you shall do with me and with the land in which you have sojourned.
English: “Swear to me.” Rabbi Chama bar Chanina said: In the days of Shimshon the oath of Avimelech began to be dissolved, because the Philistines breached the fence first, as it is said, “And he shall begin to save Israel from the hand of the Philistines.”
On the daf / in context: The covenant sworn between Avraham and Avimelech remained binding until the Philistines themselves violated it, at which point Shimshon was permitted to act against them.
Type of Learning
Derash on the verse (Bavli sugya) — not a formal named middah of the 13. The historical duration of the oath is fixed by later narrative.
What Is Learned
The oath between Avraham and Avimelech remained in force until the Philistines first violated it; only then did Shimshon begin to deliver Israel from them.