23 Then Abraham took his son Ishmael, and all the slaves who were born in his house and all who were bought with his money, every male among the men of Abraham’s household, and circumcised the flesh of their foreskin on this very same day, as God had said to him.

24 Now Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin. 25 And his son Ishmael was thirteen years old when he was circumcised in the flesh of his foreskin. 26 On this very same day Abraham was circumcised, as well as his son Ishmael. 27 And all the men of his household, those who were born in the house or bought with money from a foreigner, were circumcised with him.

Genesis 17:23 – 27 (NASB) 

Then is when?

In preparation for this promised son, in this chapter, we’ve seen the Lord give new names to Abram and Sarai, He gives a new covenant symbolized by circumcision, and renews the promises of descendents and blessings. He wants to make sure everything is in place for this promised son. Today we see Abraham’s faith in action again – just like when God called him to leave for the promised land in Genesis 12:1-5.

“Immediately, Abraham is faithful to the stipulation given to him and he applies the covenant sign and seal to his entire household. Child or servant, native or foreigner, all males are circumcised “that very day” (v. 26). The Hebrew phrase these words translate is used elsewhere to describe Noah’s entrance into the ark (Gen. 7:13) and Israel’s exodus from Egypt (Ex. 12:51).” (ligonier.org)

Ishmael vs Isaac

A deep discussion can be had about the differences between Ishmael and Isaac. Ishmael was given the covenant of circumcision which is a sign of faith (based on Abraham’s faith from Genesis 15:6 when God promised him descendents like the stars). As we noted previously, Pauls tells us in Galatians 4:22-23, “For it is written that Abraham had two sons, one by the slave woman and one by the free woman. But the son by the slave woman was born according to the flesh, and the son by the free woman through the promise.” So though they both receive the blessing of many children, Isaac is the son of the promised Messiah through whom there would be reconciliation between God and man.

Here’s a Jewish website’s perspective on the difference between the two:

For Ishmael and Isaac differed in two significant respects:

1. Ishmael came into the world by natural means, while Isaac’s birth was a supernatural event.
2. Ishmael was circumcised at the age of thirteen, the age of daat (awareness), whereas Isaac entered into the covenant of circumcision as an eight day-old infant—an age at which a person is not even aware of what is taking place, much less of its significance.

In other words, Ishmael represents a rational relationship with G‑d, one that is based upon a person’s nature and understanding. Isaac represents a supranatural, supra-rational bond.

chabad.org

RЯeflection

• “Abraham’s belief in the covenant was proved by his obedience to the command. What we really believe will show in our actions…Abraham didn’t need to pray about this. He didn’t need to grow or transition into this. God said it, and he did it. This is a wonderful example of obedience from a great man of faith.” (enduringword.com)
• Do we desire to and exercise that same kind of faith in action as Abraham?