Komentaryong Sumisipi para sa Genesis 17:19

And the Lord took account of Sarah: I have already explained in Ayelet HaShachar that when the noun precedes the verb, it indicates that the thing was earlier than this. So [here] it means to say that still before Avimelekh took her, she was already pregnant from Avraham. And that is according to the opinion of Rabbi Chama in the Midrash that she gave birth in seven truncated months. For that is why, at the time Avimelekh took her, her fetus was not noticeable. But if she gave birth in nine months, they would say that she became pregnant from Avimelekh and that she gave birth in seven truncated months. But the opinion that says she gave birth in nine month reasons that God took account of Sarah after the story with Avimelekh, and that the story with Avimelekh was ten or eleven months before her giving birth. So they would have known [this way] also that she did not get pregnant from Avimelekh. And that which the noun comes before the verb (making it past perfect) is to teach the connection of the deed [that was mentioned before it]: That by way of his praying for Avimelekh, the Lord took account of Sarah - like the matter that they said (Bava Kamma 92a), "Whoever prays for his fellow, when he himself also is in need of that very thing, will be answered first." And the Lord took account: There is a distinction between saying (amirah) and speaking (dibbur), as I wrote at length in the book, HaTorah VeHaMitzvah (Leviticus 3). As speech also signifies the explanation of the things. And there is a distinction between remembered (zakhar) and took account of (pakad). As taking account of, is always to do some thing for [the other]. So first God said, in Parashat Lech [Lecha] (Genesis 17:19), "Indeed, your wife Sarah will bear you a son." And that is called saying. But it was [only] fulfilled when He took account of her to have her conceive. And afterwards (Genesis 18:14), He spoke and explained through an angel and limited "the time that I will return to you," that it would be on Pesach of the next year. And about this it stated, "and the Lord did to Sarah as He had spoken."

To Avraham. Not to Sarah, as it says nowhere that Hashem spoke to her [about this]. The Re’m asks: Why did Rashi not explain that also Hashem’s saying was to Avraham and not to Sarah? He answers: Perhaps because it is written there (17:19), “God said, ‘Indeed your wife Sarah will bear you a son,’” [so it is obvious] that this was said to Avraham; Rashi did not need to explain it. And Rashi did not need to explain it even for Hashem’s speaking, since it is written there (15:1), “The word of Adonoy came to Avram.” Rather, Rashi comes to tell us the difference between “Hashem did for Sarah as He had spoken,” and “At the designated time that Elokim had spoken” (v. 2). The former refers to Avraham, while the latter refers to [His declaration of] the designated time, as Rashi explains there. You might ask: Why does Rashi explain this? The answer is: Rashi means that Hashem said only to Avraham, “That one [Yishmael] will not be your heir” (15:4), and never promised that the heir will come from Sarah. Nevertheless, “Hashem did for Sarah,” although He had spoken only to Avraham. (Maharshal)

The verse also reports something we have explained on 18,10 and again on 17,19, namely that the son Sarah bore originated in the female (negative) side of the emanations. This in turn was the reason Isaac needed to submit to the binding on the altar, something that resulted in Sarah's death. The word דבר always refers to speech containing some harsh element. The Torah therefore uses it when it wants us to note that the birth of Isaac was not something that was perfect. He had to undergo a process of refinement as a result of which he could become holy. When the Torah says ויעש ה׳ לשרה כאשר דבר, this really means that "G'd did to Sarah as He had foretold." Isaac was born in response to Sarah's prayer, not in response to Abraham's.

וקראת שמו AND THOU SHALT CALL — This is a command, just as one would say to a man (וְקָרָאתָ), as (Genesis 17:19) “And thou shalt call his name Isaac”.