Komentarz do Rodzaju 21:5

ואברהם בן מאת שנה, although as an old man we could have expected Avraham to delegate the task of performing his son’s circumcision, he did so himself, ignoring the fact that he was an old man. [the commentary is based on the fact that we knew that Avraham was 100 years old at the time, so why repeat it?]

ואברהם...את יצחק בנו, this verse is another example of the word את appearing in conjunction with verbs which appear in the passive mode. To name just a few such examples: Numbers 26,55 יחלק את הארץ, or Deut. 20,5 ולא ימס את לבב אחיו. What is the reason that the Torah saw fit to write this verse at all? Seeing that the Torah had told us that Avraham had been 99 years old when he had received the commandment of circumcision, and G’d had told him that Sarah would bear this son for him in the following year, we knew that he would be 100 years old at that time! (17,21) Perhaps the Torah wanted to tell us that Avraham had completed 100 years when Yitzchok was born and that the previous prophecy had been revealed to him when he had completed 99 years. In that event, Sarah’s pregnancy lasted fully 12 months, so that the news revealed in our verse is that her pregnancy was unnaturally lengthy.

And Avraham was a hundred years old: But it is no longer written, "and Sarah was ninety years old'; for behold, she had already reverted to being a youngster.

Avraham was one hundred years old: Since at the time that it was announced to Avraham that he would father a son, he fell "on his face and laughed and said in his heart, 'Can a hundred year old man have children'" (Genesis 17:17). And he laughed with joy about the miracle that He would do to him; so God told him that he should call him Yitzchak based on this laughter (tzchok). And afterwards when Sarah heard of the announcement, she also laughed with joy, as she went back to her youthfulness and would bear a child in the natural way; whereas Avraham would remain in his old age and require a miracle - as I wrote in my commentary there. According to this, it can be said that that which Avraham called the name of this son Yitzchak was because "Avraham was one hundred years old when his son Yitzchak was born to him." As he laughed and rejoiced about this - "can a hundred year old man have children?" And he was commanded to call him Yitzchak based on this. But about this, Sarah said (Genesis 21:6) that "God made for me" the main laughter and miracle - he made a greater miracle for me, to the point "that anyone who hears," will not laugh about the miracle of Avraham. Rather he "will laugh for me," about the miracle that was done for me. And she explained the thing - that even though I went back to my youthfulness, and based on this, the birth was in the natural way, nevertheless...