“Abraham fell upon his face, and he laughed. He said in his heart: Shall a child be born to one who is one hundred years old? And shall Sarah, a ninety-year-old woman, give birth?” (Genesis 17:17). “Abraham fell upon his face, and he laughed” – Abraham fell on his face twice,9In this verse and in Genesis 17:3. and corresponding to them, circumcision was twice withheld from his descendants – once in Egypt and once in the wilderness.
In Egypt, Moses came and circumcised them;10To enable them to partake of the paschal sacrifice (see Exodus 12:48). in the wilderness, Joshua came and circumcised them.11See Joshua chapter 5. “He said in his heart: Shall a child be born to one who is one hundred years old?” Rabbi Yudan and Rabbi Azarya, Rabbi Yudan said: “Shall a child be born to one who is one hundred years old” – why?12Why did Abraham express such wonderment over this?
Why should a very old man be unable to father children? Because “Shall Sarah, a ninety-year-old woman, give birth?” A man does not grow old,13That is, he does not lose his fertility with old age. but a woman grows old. Rabbi Azarya said: Regarding this, too, it was not necessary,14Abraham need not have expressed wonder about Sarah either. as Sarah at ninety years old had not grown old.
What is an old woman? It is one whom they call: Mother So-and so,15The title Mother was used to refer to old ladies. and she does not mind.