17:21,22
“But my covenant ...” God will bless Ishmael, but His plan remains the same. This balance between holding to God’s ways and being merciful is something we are inordinately bad at. We will go to one extreme or the other. On the one hand we will stick rigidly to God’s ways (in our own eyes) in a way that God would not do, and mercy goes out of the window. Or we will be “merciful” (in our own eyes) but overlook all sorts of abominations against God’s ways, or even overtly approve of them. Neither of these routes is a godly road. We need to look at the whole counsel of God. So God’s promises would be fulfilled through Isaac. Note the words “whom Sarah will bear ...” Throughout this there is a great emphasis on Sarah. Both Abraham and Sarah are pioneers in faith. When God had finished speaking to Abraham He left.
17:23-27
Abraham then went and obeyed the Lord’s instruction, circumcising his son Ishmael, and everyone else born in his household, or bought with his money. So all the males were circumcised. This included Abraham himself, and he was ninety nine years old at the time. Ishmael was thirteen. The text makes absolutely sure that we know that everyone was circumcised!