Thou shalt be a blessing. — More correctly, Be thou a blessing. The promises made to Abram are partly personal and partly universal, embracing the whole world. In return for all that he abandons he is to become the founder of a powerful nation, who will honour his name, and teach the inheritors of their spiritual privileges to share in their veneration for him. But in the command to “be” or “become a blessing,” we reach a higher level, and it is the glory of Abram’s faith that it was not selfish, and in return for his consenting to lead the life of a stranger, he was to be the means of procuring religious privileges, not only for his own descendants, but also “for all families of the earth” (Heb., of the ground — the adâmâh). Not for the earth as the material universe, but solely in its connection with man. Wherever man makes his home upon it, there, through Abram, spiritual blessings will be offered him.
I will bless... — These words indicate relations mysteriously close between Jehovah and Abram, whereby the friends and enemies of the one become so equally to the other. But in the second clause our version has not noticed an essential difference between the verbs used. They occur together again in Exodus 22:28, and are there more correctly rendered by “revile” and “curse.” The one word signifies to treat lightly and contemptuously, the other to pronounce a curse, usually in a judicial manner. We might, therefore, translate, “I will curse — pass a sentence of rejection upon — him that speaketh lightly of, or revileth thee.”
In thee shall all families of the earth be blessed. — Some authorities translate, “shall bless themselves;” but there is a different conjugation to express this meaning, and no reason exists for forcing it upon the text. Henceforward Abram and the nation sprung from him were to be the intermediaries between God and mankind, and accordingly revelation was virtually confined to them. But though the knowledge of God’s will was to be given through them, it was for the benefit of all the families of every race and kindred distributed throughout the habitable world, the adâmâh (Romans 3:29; Romans 10:12, &c).