Isaac Born on Passover and Sarah's Renewed Youth

"And He said, I will surely return to you at this season, and behold, Sarah your wife shall have a son" (Genesis 18:10). Isaac was born on Passover. How do we know? Because it is written "at the living season" [ka'et hayah]. To which appointed time does "this time" refer? If you say it was on Passover and He spoke of Shavuot, would she give birth in fifty days? Rather, He stood at Shavuot and spoke of Tishrei - but still, in five months would she give birth? Rather, He stood at Tishrei and spoke of Nisan - but still, in six months would she give birth? That year was a leap year. In the end, when you deduct the days of impurity, they fall short. Mar Zutra said: even according to the one who says a woman who gives birth at nine months does not give birth at a partial ninth month, one who gives birth at seven months does give birth at a partial seventh month, as it is said, "And it came to pass at the turn of the days that Hannah conceived and bore" (1 Samuel 1:20) - the minimum of "turns" is two and the minimum of "days" is two. "And Sarah was listening" (Genesis 18:10): from here we learn that women are eavesdroppers, and so on (as in remez 24). "And it was behind him" (Genesis 18:10): this is Ishmael. "And it was behind him" - because of privacy. "And it was behind him" - the angel sensed that light was coming. "And Abraham and Sarah were old" (Genesis 18:11). Rabbi Yohanan said: it is already written "And Abraham and Sarah were old"; why does Scripture say "And Abraham was old, advanced in days" (Genesis 24:1)? Rather, because the Holy One, blessed be He, restored them to the days of their youth, it was necessary a second time to say "And Abraham was old." Rabbi Ami said: here, old age with vigor; there, old age without vigor. "It had ceased to be with Sarah after the manner of women" (Genesis 18:11): like "if you cease to vow" (Deuteronomy 23:23), meaning it stopped, as in "and ceased to keep the Passover" (Numbers 9:13). "And Sarah laughed within herself, saying" (Genesis 18:12): this is one of the things they altered for King Ptolemy (written in remez 3). "After I am worn out shall I have pleasure" [ednah]: this woman, as long as she gives birth has adornments [takhshitin]; and I, after I am worn out, shall I have adornment [ednah]? as you say, "And I adorned you with ornaments" (Ezekiel 16:11). This woman, as long as she gives birth, has childbearing with him. Another interpretation: ednah means the menses returned. "And my lord is old" (Genesis 18:12). (Genesis 18:13) Rabbi Yehuda said in the name of Rabbi Simon: You [angels] make yourselves young and make your masters old; but I, "I have grown too old" to perform miracles? Bar Kappara said: Great is peace, for Scripture altered: she said, "and my lord is old," and the Holy One, blessed be He, said, "and I am old," in order to make peace between Abraham and Sarah. "Is anything too hard for the LORD?" (Genesis 18:14). Rabbi Yudan bar Rabbi Simon said: A parable of one who had two cleavers in his hand and brought them to a smith. He said to him, Can you repair them? He said to him, To create them anew I can, but to repair them I cannot. So: to create them anew I can, but to restore them to the days of their youth I cannot.