I will bless them that bless thee, and curse them that curse thee, and IN THEE shall all the kindred of the earth be blessed:

“Abraham, styled "the friend," [Isaiah 41:8] was found faithful, inasmuch as he rendered obedience to the words of God. He, in the exercise of obedience, went out from his own country, and from his kindred, and from his father's house, in order that, by forsaking a small territory, and a weak family, and an insignificant house, he might inherit the promises of God. For God said to him, "Get you out from your country, and from your kindred, and from your father's house, into the land which I shall show you. And I will make you a great nation, and will bless you, and make your name great, and you shall be blessed. And I will bless them that bless you, and curse them that curse you; and in you shall all the families of the earth be blessed." [Genesis 12:1-3] And again, on his departing from Lot, God said to him, "Lift up your eyes, and look from the place where you now are, northward, and southward, and eastward, and westward; for all the land which you see, to you will I give it, and to your seed forever. And I will make your seed as the dust of the earth, [so that] if a man can number the dust of the earth, then shall your seed also be numbered." [Genesis 13:14-16] And again [the Scripture] says, "God brought forth Abram, and spoke unto him, Look up now to heaven, and count the stars if you are able to number them; so shall your seed be. And Abram believed God, and it was counted to him for righteousness." [Genesis 15:5-6] On account of his faith and hospitality, a son was given him in his old age; and in the exercise of obedience, he offered him as a sacrifice to God on one of the mountains which He showed him. [Genesis 22:9]”

“ונברכו בך AND IN THEE SHALL BE BLESSED — There are many Agadoth concerning this but the plain sense of the text is as follows: A man says to his son, “Mayest thou become as Abraham”. This, too, is the meaning wherever the phrase ונברכו בך “And in thee shall be blessed” occurs in Scripture, and the following example proves this: (Genesis 48:20) בך יברך “By thee shall Israel bless their children saying, “May God make thee as Ephraim and Manasseh”.”

“And I will bless them that bless thee,.... Not the priests only that should bless his children, the children of Israel, as the Targum of Jonathan, but all men of all nations, and of every age, that speak well of him, commend him for his faith and holiness, and tread in his steps, these are blessed with faithful Abraham, Gal 3:7. And curse him that curseth thee; here is a change of numbers, before the plural, here the singular, denoting, it may be, that many would bless him, and but few curse him, and that every individual person that did curse him should be cursed himself: the Targum of Jonathan wrongly restrains this to Balaam's cursing Abraham's children, and was cursed by God; Maimonides (y) thinks, there is no doubt to be made of it, that the Zabaeans, the idolatrous people Abram was brought up with, when he contradicted them, loaded him with curses and reproaches; and, because he bore them all patiently for the glory of God, as became him, therefore these words are said; but they, without question, respect future as well as present times, and regard all such, in every age and of every nation, that disapproves of, or rejects and reproaches Abram's God, his faith, his religion, and his people. And in thee shall all families of the earth be blessed; that is, in his seed, as in Gen 22:18 and which is interpreted of Christ, Act 3:25 meaning not every individual of all the families or nations of the earth; but that as many as believe in Christ, of all nations, are blessed in him; and that whoever of them are blessed, they are blessed and only blessed in him, and that they are blessed for his sake with all spiritual blessings; see Eph 1:3 such as redemption, justification, remission of sins, sanctification, adoption, and eternal life. (y) More Nevochim, ut supra. (par. 3. c. 29. p. 421.)”

“In thee - In thy posterity, in the Messiah, who shall spring from thee, shall all families of the earth be blessed; for as he shall take on him human nature from the posterity of Abraham, he shall taste death for every man, his Gospel shall be preached throughout the world, and innumerable blessings be derived on all mankind through his death and intercession.”

“In thee, &c., or in the Messias, who will be one of thy descendants, and the source of all the blessings to be conferred on any of the human race, Galatians iii. 16. Many of the foregoing promises regarded a future world, and Abram was by no means incredulous, when he found himself afflicted here below, as if God had forgot his promises. (Calmet) — He was truly blessed, in knowing how to live poor in spirit, even amid riches and honours; faithful in all tribulations and trials; following God in all things, ver. 1.”