Ishmael was also circumcised.
So were his gentile servants. You might consider the promise to Abraham himself concerns a land and promises of the next world and the next life.
And no.....I am not a Hamas supporter. But I do support looking at things in a historical context.
Abraham, Isaac, and Jacob will be dead When this promised seed comes into effect.
The earthly, worldly land grant.
Gen 15.
Abe, Isaac, Jacob, and the generation of the patriarchs will be dead.......
15 And thou shalt go to thy fathers in peace; thou shalt be buried in a good old age.
16 But in
the fourth generation they shall come hither again: for the iniquity of the Amorites is not yet full.
Joseph understood this
Ex. 1:6 And Joseph died, and all his brethren, and all that generation. The 3rd generation dies.
Ge 50:25 And
Joseph took an oath of the children of Israel, saying, God will surely visit you, and ye shall carry up my bones from hence.
Ex 13:19 And
Moses took the bones of Joseph with him: for he had straitly sworn the children of Israel, saying, God will surely visit you; and ye shall carry up my bones away hence with you.
By this time the Ishmaelites were not keeping the covenant of circumcision.
Because Abraham obeyed......
God kept the covenant made with him through Isaac.
There is more IMO Birthright, firstborn , two portions of inhertance. Circumcision merely an outward symbol of a double inheritance. Cant be double without two right?