ציטירנדיקער פּירוש אויף בראשית 20:18

וה' פקד את שרה כאשר אמר, “and G’d had remembered Sarah just as He had said.” This means she became pregnant.
ויעש ה' לשרה כאשר דבר, “and G’d did for Sarah as He had spoken.” This is a reference to her giving birth. This is why the Torah immediately follows by recording: “she became pregnant and gave birth.” The reason the Torah wrote this paragraph immediately after having informed us of the closing of the birth-canals in Avimelech’s household, etc., is to remind us that both the “so-called” natural process of becoming pregnant and giving birth and the inability to do so are in G’d’s hands. He alone is in charge of who becomes pregnant and who does not.

And the Lord took account of Sarah, etc. [until] and Sarah saw the son of Hagar the Egyptian (Genesis 21:1-9): Since it stated above (Genesis 20:18) that, "The Lord surely sealed every womb in the house of Avimelekh for the matter of Sarah, the wife of Avraham," it juxtaposed it to, "And the Lord took account of Sarah" - meaning to say that the Lord sealed up her enemies, but took account of her, that she should give birth when she was barren. And [the Sages,] may their memory be blessed, said that one who prays for the sake of his fellow is first answered himself. And so it was that since Avraham prayed for Avimelekh, the Lord took account of Sarah his wife. And the expression, taking account (pekidah) is truthfully, visiting and paying attention, as in "I have surely taken account of (pekod pakadati) you and that which is being done to you in Egypt" (Exodus 3:16). For it is since they thought that He, may He be blessed, was not paying attention to them that He said this. And this is like, "and Shimshon took account of his wife with goat clothing" (Judges 15:1); "Lord, in distress did they take account of You." Until on account of this did [people] call those counted, pekudim, and those counting them, pokedim. And the explanation of this verse is that the angel of God had said in God's name, "I will surely return to you next year" (Genesis 18:10). And the content of this returning and this coming is the benefit that He will give him a son from Sarah. For the action indicates the presence of the actor; and since the action was here, the Actor was [also] here. And that is why it is stated (Joshua 6:27), "And the Lord was with Yehoshua"; "And the Lord was with Yosef" (Genesis 39:2) - in that His goodness and His attention was with him. And that is the meaning of, "And the Lord took account of Sarah" - that He payed attention to her matter and that which He had forecast for her. But since there is a taking account for the good and a taking account for the bad - as He stated (Exodus 32:24), "but on the day of My taking account, I will take account" - it was necessary to explain here that the taking account of Sarah was when "the Lord did to her like He had spoken," when He gave her the son that He had forecast to her. And He did not mention that He took account of Avraham for [the following reason]: Because the retention and the pregnancy is with the woman; also because the thing was stranger and more difficult from the perspective of Sarah than it was from the perspective of Avraham. And it is [also] possible to explain, "And the Lord took account of Sarah as He had said," by giving her seed, "and the Lord did to Sarah as He had spoken" - that He gave her a male child, and not a daughter. And his name was called Yitzchak, because that is what He said to her. However, from the perspective of Avraham, it said, "And Sarah conceived and bore Avraham a son in his old age" - meaning to say that she gave birth to the son mentioned from him even with all of his age. And that is the reason for its stating, "in his old age." As it did not say it to denote the time at which she gave birth, but rather to say that also this kindness and this taking account - from the perspective of his being elderly - was done for him. And it is also possible that this is to say that Yitzchak would be the child of his old age, and that is a child that helps his father and serves him; so he would need him for his old age. And with this explanation, it is indicated that its stating, "At the set-time of which God had spoken" - that this is the mention of the time at which he was born; not that which it says, "in his old age." And two questions are solved with this, the first and the second.

ויתפלל בעדך, and he will pray on your behalf. Avimelech and entourage were in need of G’d’s mercy, as we know from verse 18.

let no man rule against You Let not our enemies - man - have human strength to rule (עִמְּךָ) with You, i.e., against You, to be victorious, so that they should not say, “We have defeated their God.” Another explanation from the Rabbi: Let not the weak one (אֱנוֹשׁ) be held back (יַעְצר), for we are weak, deprived of strength, keeping us back (עוֹצְרֵי יָד) from defeating them. And an example is (Deut. 11:17): “and He will hold back (וְעָצַר) the heaven”; (Gen. 20:18): “For the Lord had held back (וְעָצר עָצַר),” and like (Jud. 13:16): “If you take me in (תַּעְצְרֵנִי).”

and He reproved kings on their account (Gen. 12:17): “And the Lord plagued Pharaoh”; (ibid. 20:18), “For the Lord had closed up every womb of the house of Abimelech.”

ויסגור ה' בעדו AND THE LORD SHUT HIM IN — He protected him so that they could not smash up the Ark (cf. 5:13): He surrounded the Ark (thus enclosing it סגר) with bears and lions which killed some of them (Genesis Rabbah 32:8). But the literal meaning of the text is: He shut the door in front of him against the waters. Similarly, wherever בעד occurs in the Scriptures it means כנגד in front of. E. g., (20:18) “The lord had made a closure in front of (בעד) every womb”; (2 Kings 4:4) “Close the door in front of thyself (בעדך) and in front of (ובעד) thy sons”; (Job 2:4) ‘‘skin in front of (as a protection for) (בעד) skin”; (Psalms 3:4) “a shield in front of me ובעדי”: (1 Samuel 12:19) “Pray (בעד) thy servants” which means כנגד in front of (i. e. on behalf of, as a protection for) thy servants.

He let no man oppress them Although they walked from place to place and it is customary to harm wayfarers, and when they arrive to their inn, they are falsely accused, but these the Holy One, blessed be He, did not let [anyone] hurt them or oppress them. An example is (Lev. 5:21): “or oppressed (עָשַּׁק) his neighbor.” Now if you ask if the reason that the highwaymen and [the people of] the other lands in whose midst they passed did not harm them was that they did not notice them, but if they had noticed them, they would have oppressed them, therefore, it says: “... and He reproved kings on their account,” i.e., they did oppress them, as Pharaoh [did] to Abraham and Abimelech to Isaac, and Laban and Shechem to Jacob, and the Holy One, blessed be He, said to them...