Genesis 17:4
17:4 As for me, behold, my covenant [is] with thee, and thou
     shalt be a {a} father of many nations.

     (a) Not only physical descendants, but of a far greater
         multitude by faith, Romans 4:17.

Genesis 17:5
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.

     (b) The changing of his name is a seal to confirm God's
         promise to him.

Genesis 17:10
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.

Genesis 17:11
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.

Genesis 17:14
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 God's promise: for under mankind all was
          consecrated. Here it is declared, that whoever
          condemns the sign, also despises the promise.

Genesis 17:17
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.

Genesis 17:19
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.

Genesis 17:23
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 Abraham's 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.