אמר רבי יצחק יצחק אבינו עקור היה שנאמר (בראשית כה, כא) ויעתר יצחק לה' לנכח אשתו על אשתו לא נאמר אלא לנוכח מלמד ששניהם עקורים היו א"ה ויעתר לו ויעתר להם מיבעי ליה לפי שאינו דומה תפלת צדיק בן צדיק לתפלת צדיק בן רשע א"ר יצחק מפני מה היו אבותינו עקורים מפני שהקב"ה מתאוה לתפלתן של צדיקים א"ר יצחק למה נמשלה תפלתן של צדיקים כעתר מה עתר זה מהפך התבואה ממקום למקום כך תפלתן של צדיקים מהפכת מדותיו של הקב"ה ממדת רגזנות למדת רחמנות
Rabbi Yitzḥak said: Isaac our father was infertile, as it is stated: “And Isaac entreated the Lord concerning [lenokhaḥ] his wife because she was barren” (Genesis 25:21). It is not stated that he entreated the Lord for [al] his wife, but lenokhaḥ, which can mean opposite, against, or corresponding to; this teaches that they were both infertile. The Gemara asks: If so, why does the verse continue: “And the Lord let God's self be entreated of him”? The verse should say: And the Lord let God's self be entreated of them. The Gemara answers that their prayers were answered due to Isaac, because the prayer of a righteous individual who is the child of a righteous individual is not similar to the prayer of a righteous individual who is the child of a wicked individual, and Rebekah’s father was the wicked Laban. Rabbi Yitzḥak said: For what reason were our forefathers initially infertile? Because the Holy Blessed One, desires the prayers of the righteous, and God therefore wanted them to pray for children. Similarly, Rabbi Yitzḥak said: Why are the prayers of the righteous compared to a pitchfork [eter], as in the verse: “And God let God's self be entreated [vaye’ater]”? This indicates that just as this pitchfork turns over produce from one place to another, so the prayer of the righteous turns over the attributes of the Holy Blessed One, from the attribute of rage to the attribute of mercy.
(ה) וַיֶּעְתַּר יִצְחָק לַה' לְנֹכַח אִשְׁתּוֹ (בראשית כה, כא), רַבִּי יוֹחָנָן וְרֵישׁ לָקִישׁ, רַבִּי יוֹחָנָן אָמַר שֶׁשָּׁפַךְ תְּפִלּוֹת בְּעשֶׁר. רֵישׁ לָקִישׁ אָמַר שֶׁהִפֵּךְ אֶת הַגְּזֵרָה, וּלְפוּם כֵּן קָרְיִן לֵיהּ עַתְרָא דְּאַפֵּךְ אִדְּרָא. לְנֹכַח אִשְׁתּוֹ, מְלַמֵּד שֶׁהָיָה יִצְחָק שָׁטוּחַ כָּאן, וְהִיא שְׁטוּחָה כָּאן, וְאוֹמֵר רִבּוֹנוֹ שֶׁל עוֹלָם כָּל בָּנִים שֶׁאַתָּה נוֹתֵן לִי יִהְיוּ מִן הַצַּדֶּקֶת הַזּוֹ, אַף הִיא אָמְרָה כֵּן, כָּל בָּנִים שֶׁאַתְּ עָתִיד לִתֵּן לִי יִהְיוּ מִן הַצַּדִּיק הַזֶּה.
(5) "Isaac pleaded with the LORD on behalf of his wife" (Genesis 25, 21), Rebi Yochanan and Reish Lakish- Rebi Yochanan says that (the word 'plead' means) he poured forth a wealth of prayers. Reish Lakish says it means that his prayers overturned God's decree, and therefore a winnowing shovel is referred to as an עתרא, for it overturns the grain in the threshing place.
"on behalf of his wife" This teaches that Isaac was prostrated in prayer here and [Rebecca] was prostrated in prayer there. And Isaac said in his supplication: "Master of the universe! [May] all the children that You will give to me be from this righteous woman." [Rebecca] too said thus: "May all of the children that You will give to me in the future be from this righteous man."
(יא) רבי יהודה אומר, עשרים שנה היתה רבקה עקרה, לאחר עשרים שנה לקחה יצחק והלך עמה להר המוריה למקום שנעקד שם, והתפלל על ההריון ונעתר לו, שנאמ׳ ויעתר לו ה׳ וגו׳.
(11) Rabbi Jehudah said: Rebecca was barren for twenty years. After twenty years (Isaac) took Rebecca and went (with her) to Mount Moriah, to the place where he had been bound, and he prayed on her behalf concerning the conception of the womb; and the Holy Blessed One, was entreated of him, as it is said, "And Isaac entreated the Lord" (ibid. xxv. 21).
כי עקרה היא. משום שהיתה מארם ואחות לבן הארמי. והיה בדרך הטבע שיהיו בניה אכזרים ע״כ נתעקרה. והיה לידתה אח״כ בדרך פלא ונס וממילא לא היה בטבע הראוי:
For she was barren. because she was from Aram and the sister of Laban, the Aramean. It was natural that her children should be cruel and thus she was barren. Her pregnancy after this was a wonder and a miracle and was not according to the natural process.
(כב) ויתרוצצו עַ"כָּ הַמִּקְרָא הַזֶּה אוֹמֵר דָּרְשֵׁנִי, שֶׁסָּתַם מַה הִיא רְצִיצָה זוֹ וְכָתַב אִם כֵּן לָמָּה זֶה אָנֹכִי? רַבּוֹתֵינוּ דְרָשׁוּהוּ לְשׁוֹן רִיצָה; כְּשֶׁהָיְתָה עוֹבֶרֶת עַל פִּתְחֵי תוֹרָה שֶׁל שֶׁם וְעֵבֶר, יַעֲקֹב רָץ וּמְפַרְכֵּס לָצֵאת, עוֹבֶרֶת עַל פֶּתַח עֲבוֹדַת אֱלִילִים, עֵשָׂו מְפַרְכֵּס לָצֵאת דָּבָר אַחֵר מִתְרוֹצְצִים זֶה עִם זֶה וּמְרִיבִים בְּנַחֲלַת שְׁנֵי עוֹלָמוֹת
(22) ויתרצצו AND [THE CHILDREN] STRUGGLED — You must admit that this verse calls for a Midrashic interpretation since it leaves unexplained what this struggling was about and it states that she exclaimed “If it be so, wherefore did I desire this” (i.e. she asked whether this was the normal course of child-bearing, feeling that something extraordinary was happening). Our Rabbis explain that the word ויתרוצצו has the meaning of running, moving quickly: whenever she passed by the doors of the Torah (i. e. the Schools of Shem and Eber) Jacob moved convulsively in his efforts to come to birth, but whenever she passed by the gate of a pagan temple Esau moved convulsively in his efforts to come to birth (Genesis Rabbah 63:6). Another explanation is: they struggled with one another and quarrelled as to how they should divide the two worlds as their inheritance (Yalkut Shimoni on Torah 111:2).
(27) When the boys grew up, Esau became a skillful hunter, a man of the outdoors; but Jacob was a mild man who stayed in camp. (28) Isaac favored Esau because he had a taste for game; but Rebekah favored Jacob. (29) Once when Jacob was cooking a stew, Esau came in from the open, famished.
(א) ויאהב יצחק את עשו גם את עשו אע''פ שידע בלי ספק שלא היה שלם כיעקב:
(1) ויאהב יצחק את עשו, also Esau, not only Yaakov, even though he must have been aware that Esau was far less perfect than Yaakov.
(ב) ידע ציד. לצוד ולרמות את אביו בפיו, ושואלו אבא היאך מעשרין את המלח ואת התבן, כסבור אביו שהוא מדקדק במצות:
A skillful hunter: [He knew how] to trap and to deceive his father with his mouth and ask him,“Father, how do we tithe salt and straw?” His father thereby thought that he was scrupulous in his observance of the commandments.
Robert Alter, The Five Books of Moses, p.130
for the game that he brought him: The Hebrew says literally, "for the game in his mouth." It is unclear whether the idiom suggests Esau as a kind of lion bringing home game in its mouth or rather bringing game to put in his father's mouth. The almost grotesque concreteness of the idiom may be associated with the material reason for Isaac's paternal favoritism. Pointedly, no reason is assigned for Rebekah's love of Jacob in the next clause.
Rabbi Isaiah Horowitz, "The Sh.L.aH." on Genesis 25:28
Isaac favored Esau because he had a taste for game; but Rebekah favored Jacob.
Isaac's love was a love dependent on an external factor "כִּי־צַ֣יִד בְּפִ֑יו." Of such a love, we are told, once the external factor disappears, the love disappears as well. Rebekah, on the other hand, loved Jacob without an external factor being the cause of her love. Such love remains forever. This is why the Torah uses the form, "אֹהֶ֥בֶת" to describe her love - which is in the present, continuous, tense - to signify that Rebekah's love for Jacob was an eternal one.
(א) ויאהב יצחק את עשו כי ציד בפיו. לפי כשהיה שואלו אביו מה אתה עושה בשדה כל היום היה מתנצל ואומר כדי לצוד ציד להביא טרף לפיו של אביו, ולפי שלא היה מצוי אצל אמו על כן לא אהבה אותו רבקה והיתה אוהבת את יעקב שהיה מצוי אצל אמו וכל געגועיה עליו ...
Isaac favored Esau because he had a taste for game: When his father asked him, "What do you do in the field all day?" He would apologize, saying, "It takes me all day to hunt animals and bring meat to my father's mouth." Since his mother rarely saw him, she did not love him, only Jacob, because he spent his time with her, and she poured all her affection upon him.
Rabbi Naftali Tzvi of Ropshitz
Isaac, who grew up in the house of Abraham, surrounded by the righteous and pure, did not know the ways of tricksters, and therefore fell for Esau's trickery. But Rebecca, she grew up in the house of Bethuel and Laban. She knew tricksters and their lies. She was able to see through Esau and his lies.
According to a Midrash Tanchuma Toldot 8 the words מורת רוח mean מרימת רוח, “they caused the holy spirit which had previously rested on Yitzchak as well as on Rivkah to lift itself off Yitzchak and Rivkah and to depart from them.” Departure of holy spirit from a person may be due to two reasons. 1) Because a person becomes angry and loses their “cool.” We have a tradition that holy spirit rests on a person only when one is in a joyous frame of mind (Berachot 31). 2) Another reason why the holy spirit departs from a person is when one keeps company with wicked persons. We have observed a classic example of this when the Torah did not report G’d as communicating with Avraham until the latter had separated himself from Lot (compare Genesis 13,14). Bereshit Rabbah 65,4 states that one of Esau’s wives was a daughter of a priest. Seeing that Rivkah herself was a daughter of an idolatrous priest, she did not mind so much when she saw garbage of idolatry. Yitzchak, since he was the son of holy people was bothered by the garbage of idolatry, thus Yitzchak is bothered first.
(כז) והתשובה בזה, שמבואר הוא בפסוק (בראשית כה כח) כי יצחק היה אוהב את עשו, ואין ספק שלא היה מכיר את מעשיו הרעים כמו שהודיעונו רבותינו ז"ל (תנחומא תולדות על הכתוב בראשית כה כח). ואילו באתהו הנבואה שיניח בנו בכורו אשר אהב ויברך את יעקב, אין ספק שהיה מתעצב בזה, ויהיה עצבונו סיבה שלא תחול עליו רוח השם יתברך על השלמות, ולזה רצה השם יתברך שיהיה סבור לברך בנו עשו אהובו, כדי שיתרחב לבו וישמח, וישיג רוח אלהי בתכלית מה שהיה אפשר לו להשיג. והיא הסיבה במה שאמר יצחק לעשו (שם כז ד) ועשה לי מטעמים כאשר אהבתי והביאה לי ואוכלה בעבור תברכך נפשך, כדי שתתרחב נפשו ותשמח, ויחול עליו רוח נבואיי.
(27) The answer: Scripture makes it clear that Isaac loved Esau, undoubtedly not knowing of his evil deeds, as our sages have apprised us (Tanchuma, Toldoth 8). And if there had come to him a prophecy that he put aside his eldest son, whom he loved, and bless Jacob instead, there is no doubt that this would have saddened him; and this sadness would have prevented the spirit of the L-rd from coming to rest upon him in perfection. For this reason the Blessed One desired him to think that he was blessing his beloved son, Esau, so that his heart expand in joy and he attain the G-dly spirit to the full extent of his powers. And this is, likewise, the reason for Isaac's saying to Esau (Genesis 27:4): "And make me savory food, as I love, and bring it to me and I will eat it, so that my soul bless you." That is, so that his soul expand and rejoice and the spirit of prophecy come to rest upon it. And it is because of this factor that the Blessed One desired that Jacob think he was blessing Esau when he was, in reality, blessing Jacob.