Genesis 12:3

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, ( Galatians 3:7 Galatians 3:9 ) .

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 ^F25 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 ( Genesis 22:18 ) and which is interpreted of Christ, ( Acts 3:25 ) ( Galatians 3:8 Galatians 3:16 ) 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 ( Ephesians 1:3 ) such as redemption, justification, remission of sins, sanctification, adoption, and eternal life.