In Breishit 21:23–24, Avimelech asks Avrahm to swear that his future generations will not destroy his sons or grandchildren.

Bechor Shor commentary says:

תעשה עמדי. כשתבא לידך שלא תגרש גם אתה את זרעי:

When you possess (the land, swear) that that you will not exile my offspring.

If Avraham made this promise, how was King David, or anyone else allowed to destroy / exile the Philistines?

  • 1
    ולניני ולנכדי. עַד כָּאן רַחֲמֵי הָאָב עַל הַבֵּן: NOR WITH MY SON NOR WITH MY SON’S SON — thus far extends a man’s pity for his descendants (Genesis Rabbah 54:2). Perhaps that's all the Bekhor Shor means by זרעי as well.
    – Loewian
    Commented Nov 21, 2019 at 14:53
  • Were all of the Philistines descendants of Avimelech?
    – הראל
    Commented Nov 21, 2019 at 17:43
  • My understanding was that it was a 2 way agreement that was broken when they messed with the wells by Yitzchak. I have no source for this, just what I assumed.
    – mroll
    Commented Nov 21, 2019 at 22:06

2 Answers 2


As suggested in the comments above, Chazal understand the oath to be limited to 3 generations. One of earlier sources that say this:

מכילתא דרבי ישמעאל בשלח - מסכתא דויהי פתיחתא ד"א כי קרוב הוא קרובה השבועה שנשבע אברהם לאבימלך שנא' ועתה השבעה לי באלהים הנה אם תשקור לי לניני ולנכדי (בראשית כא כג) ועדיין נכדו קיים

See also Radak to Sefer Yehoshua 15:63 who mentions David specifically


Ramban on Devarim 2:23 wrote:

"...ומפני השבועה שנשבע אברהם לאבימלך לא יכלו ישראל ללכת בארצם ולהוציאם מארצם הבאתי עליהם כפתורים והשמידום וישבו תחתם ועכשיו אתם מותרים לקחת מידם...כי הכפתורים והפלשתים השמידו מן הכנענים כי אבימלך מלך גרר היה והעזתי יושב בעזה וצידון עיר פלשתים ואלה מגבול הכנעני הם שנאמר ויהי גבול הכנעני מצידון באכה גררה עד עזה והנראה בעיני כי פלשתים וכפתורים יחשבו עם אחד וכן אמר הכתוב (ירמיהו מז ד) כי שודד ה' את פלשתים שארית אי כפתור וזה טעם כפתורים היוצאים מכפתור כי יצאו מכפתור עם מעט לגור באשר ימצאו והשמידו את העוים היושבים עד עזה שהם מזרע כנען וישבו תחתם בעזה ואשקלון ואשדוד וגת ועקרון והכל מגבולות כנען וחלקו אותה לחמשה סרניהם ושם הגלילות ההם פלשת ונקראו גם הם פלשתים ונשאר לעוים יתר ארצם..."

Translation: "...and because of the oath Avraham swore to Avimelech, Yisrael couldn't go and remove them from their land, therefore I [Hashem] brought upon them the Caphtorim, and they destroyed them and settled in their stead, and now you are allowed to take from their hands...because the Caphtorim and the Plishtim destroyed of the Canaanites for Avimelech was the king of Gerar and the Gazites dwelled in Gaza and Sidon a city of the Plishtim, and these were part of the boundaries of Canaan, as it says: "The Canaanite territory extended from Sidon as far as Gerar, near Gaza" and it seems to me that the Plishtim and the Caphtorim were considered one people, and so it says (Yirmiyahu 47:4): "For the LORD will ravage the Philistines, The remnant from the island of Caphtor" and that's why it says "Caphtorim who came from Caphtor", because small remnants came from Caphtor to settle where they could and they destroyed the Avites who dwelled until Gaza who were of the seed of Canaan and settled in their stead in Gaza and Ashkelon and Ashdod and Gat and Ekron, and all of these are of the boundaries of Canaan and they divided it among their five governors and those territories where known as Peleshet and so they too became known as Plishtim and to the Avites remained the rest of their land..."

In short, we see that according to Ramban, the Plishtim who warred with Yisrael since they began conquering Canaan were not the same Plishtim from the time of Avraham. Because of this, there was no problem in engaging them in battle.

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