Continuing with verse 9 of Genesis 17.
God made clear that Abraham and his descendants were to ‘keep’ His covenant. So, obedience was involved. The ‘token’ or sign of the covenant would be circumcision. God gave Abraham instructions regarding circumcision of a new born male child within his household (descendant or stranger). If any male children were not circumcised, they would be ‘cut off’ because that would be breaking the sign of the covenant, which breaks the covenant.
The physical land rights were conditional upon their obedience. On the eternal scale, the city (land) was a promise to Abraham’s seed (if you are Christ’s, you are Abraham’s seed), this is the inheritance of a ‘new heaven and new earth’ with the city of God (the New Jerusalem) which God made that will rest upon the new earth. And the saints will reign with Christ forever. Amen and Amen.
God continues and tells Abraham, that Sarai’s (my princess) name will be changed to Sarah (noblewoman, princess). And, He will bless Sarah with a son, she will be blessed and she will be a mother nations and kings of people. Abraham fell down and laughed, saying in his heart how will a child be born to us at 100 and 90 years of age? Then, Abraham suggested to God that Ishmael might live to be the one! God plainly responded that Sarah will bear a son for sure, and Abraham was to name this child, Isaac. The covenant would be established with him and his seed as an everlasting covenant.
God then addresses the blessing for Ishmael. Ishmael would have innumerable descendants as well, he will have twelve sons, and will also be a great nation. However, he would not be the heir of promise.
The heir of promise will be Isaac, which Sarah will bear at this set time next year. This was the end of what God had to say to Abraham. And, God left (went up from him).
Abraham took Ishmael, males in his household and circumcised them that same day. Abraham was 99 when he was circumcised and Ishmael was 13.