Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin.
We have here Abraham's obedience to the law of circumcision. He himself and all his family were circumcised, so receiving the token of the covenant and distinguishing themselves from other families, that had no part nor lot in the matter. 1. It was an implicit obedience: He did as God had said to him, and did not ask why or wherefore.
Commenting on Genesis 17:23-27
And Abraham was ninety years old and nine,.... See Gen 17:1. This circumstance of his age is observed the more to commend his faith and obedience, that though he was an old man, he did not consider his age, or make that an objection; that he was unable to bear the pain, or it would be shameful for a man of his years to be...
Gen 17:22-27 When God had finished His address and ascended again, Abraham immediately fulfilled the covenant duty enjoined upon him, by circumcision himself on that very day, along with all the male members of his house. Because Ishmael was 13 years old when he was circumcised, the Arabs even now defer circumcision to a much later period than the Jews, generally till between the ages...
Commenting on Genesis 17:22-27