Commentaire sur La Genèse 26:4

והתברכו בזרעך AND IN THY SEED SHALL BLESS THEMSELVES — A man will say to his son, “May your seed be as the seed of Isaac”. Such is the meaning of this phrase wherever it occurs in the entire Scriptures. The following passage is that from which this meaning may be derived for all such passages: (47:20) “By thee shall all Israel bless their children saying, “May God make thee [as Ephraim and Manasseh]”. So, too, in the case of a curse do we find a similar idea: (Numbers 5:27) “And the woman shall become a curse”, meaning that one who curses his enemy will say “May you be like such and such a woman”. Similar, also, is (Isaiah 65:15) “And ye shall leave your name for a curse unto mine elect”, meaning that one who takes an oath will say “May I be like such-and-such a person if I have really done so-and-so”.

והרבתי...ונתתי לך לזרעך, for them it will be an outright gift as they will not only dwell there but will expel the gentiles from this land. The word זרעך is intended to apply to the descendants of Yaakov, seeing that this is the only seed common to Avraham, Yitzchok, and Yaakov. והתברכו, I have explained this on 23,18.

A man will say to his son, “May your children be like the children of Yitzchok.” Rashi is explaining that the nations will receive oral blessings [from one another], not that they will become blessed because your children [are a source of blessing for them]. For then it should say והתברכו מזרעך.

הארצות האל, “these lands;” this was to make plain that the lands over which the King of the Philistines ruled at that time were included in the land G-d had promised to the descendants of Avraham. Our author had already explained this in his commentary on Genesis 22,1.

The word: האל, is an allusion to the 31 Kings Joshua would defeat and whose lands he would conquer after Moses’ death.

והתברכו בזרעך, “and through your descendants will be blessed;” Rabbi Yoseph son of Tuviah said: “through your descendants all the nations of the world will receive genetic input.” As we learned in the Mishnah (Sotah 43) אחד המבריך ואחד המרכיב, it does not matter whether he bends or grafts the vine.