17:4 As for me, behold, my covenant [is] with thee, and thou shalt be a a father of many nations.
17:5 Neither shall thy name any more be called Abram, but thy name shall be b Abraham; for a father of many nations have I made thee.
(a) Not only physical descendants, but of a far greater multitude by faith, ( Romans 4:17 ).
(b) The changing of his name is a seal to confirm Gods promise to him. 17:10 c This [is] my covenant, which ye shall keep, between me and you and thy seed after thee; Every man child among you shall be circumcised.
(c) Circumcision is called the covenant, because it signifies the covenant and has the promise of grace joined to it: a phrase that is common to all ordinances. 17:11 And ye shall circumcise the flesh of your d foreskin; and it shall be a token of the covenant betwixt me and you.
(d) That private part is circumcised, to show that all that is begotten by man is corrupt, and must die. 17:14 And the uncircumcised e man child whose flesh of his foreskin is not circumcised, that soul shall be cut off from his people; he hath broken my covenant.
(e) Though women were not circumcised, they still partook of Gods promise: for under mankind all was consecrated. Here it is declared, that whoever condemns the sign, also despises the promise. 17:17 Then Abraham fell upon his face, and f laughed, and said in his heart, Shall [a child] be born unto him that is an hundred years old? and shall Sarah, that is ninety years old, bear?
(f) Which proceeded from a sudden joy, and not from lack of faith. 17:19 And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an g everlasting covenant, [and] with his seed after him.
(g) The everlasting covenant is made with the children of the Spirit. A temporary promise is made with the children of the flesh, as was promised to Ishmael. 17:23 And Abraham took Ishmael his son, and all that were born in his house, and all that were bought with his money, every male among the men of Abrahams house; and h circumcised the flesh of their foreskin in the selfsame day, as God had said unto him.
(h) They were well taught if they obeyed and were circumcised without resistance. This teaches that masters in their houses ought to be as preachers to their families, that from the highest to the lowest they may obey the will of God.