Genesis 12:3
2 Then I will make you into a great nation, and I will bless you, and I will make your name great, so that you will exemplify divine blessing. 3 I will bless those who bless you, but the one who treats you lightly I must curse, so that all the families of the earth may receive blessing through you.” 4 So Abram left, just as the Lord had told him to do, and Lot went with him. (Now Abram was 75 years old when he departed from Haran.)
Romans 11:15
15 For if their rejection is the reconciliation of the world, what will their acceptance be but life from the dead? 16 If the first portion of the dough offered is holy, then the whole batch is holy, and if the root is holy, so too are the branches. 17 Now if some of the branches were broken off, and you, a wild olive shoot, were grafted in among them and participated in the richness of the olive root, 18 do not boast over the branches. But if you boast, remember that you do not support the root, but the root supports you.
Yevamot 63a
Babylonian TalmudAnd Rabbi Elazar said: What is the meaning of that which is written: “And in you shall all the families of the earth be blessed [nivrekhu]” (Genesis 12:3)? The Holy One, Blessed be He, said to Abraham: I have two good shoots to graft [lehavrikh] onto you: Ruth the Moabite, the ancestress of the house of David, and Naamah the Ammonite, whose marriage with Solomon led to the ensuing dynasty of the kings of Judea. “All the families of the earth” means: Even families that live in the earth, i.e., who have land of their own, are blessed only due to the Jewish people. Similarly, when the verse states: “All the nations of the earth shall be blessed in him” (Genesis 18:18), it indicates that even ships that come from Galia to Hispania are blessed only due to the Jewish people.
Notes and References
"... In the eyes of the sages, Abraham was to be a blessing to all nations by converting them to faith in God. In support of this view, the traditional sources raise yet another nuance of meaning in the oracle God gave to Abraham. Genesis 12:3 says, "And all peoples on earth will be blessed through you." The Hebrew verb translated as "will be blessed" is related to a Mishnaic Hebrew term Onavrich that means "to intermingle, to graft." Thus, one might translate the verse as "All peoples on earth will be grafted into you." The context of the passage makes this alternative reading impossible. Clearly, the Torah intends us to read, "All peoples on earth will be blessed through you." The passage has nothing to do with the grafting of plants. It is a passage about blessing and being blessed. A responsible translator would never translate the verse to read, "All peoples on earth will be grafted into you." However, the sages are seldom accused of being responsible translators ... Rabbi Elazar uses the passage to explain how two Gentile women came to be regarded as part of Israel and even mothers of the Davidic kings. Ruth was a Moabite. Naamah was an Ammonite. The Torah says, "No Ammonite or Moabite or any of his descendants may enter the assembly of the LORD, even down to the tenth generation. How then could Ruth and Naamah be mothers of the Kings of Israel? The answer is that they were no longer to be considered Moabite and Ammonite. They had been grafted into Abraham ..."
Lancaster, D. Thomas Grafted In: Israel, Gentiles, and the Mystery of the Gospel (pp. 28-29) First Fruits of Zion, 2003