What's up with Isaac? Divrei Yoel on Toldot
(כב) וַיִּתְרֹֽצֲצ֤וּ הַבָּנִים֙ בְּקִרְבָּ֔הּ וַתֹּ֣אמֶר אִם־כֵּ֔ן לָ֥מָּה זֶּ֖ה אָנֹ֑כִי וַתֵּ֖לֶךְ לִדְרֹ֥שׁ אֶת־יְהוָֽה׃ (כג) וַיֹּ֨אמֶר יְהוָ֜ה לָ֗הּ שְׁנֵ֤י גיים [גוֹיִם֙] בְּבִטְנֵ֔ךְ וּשְׁנֵ֣י לְאֻמִּ֔ים מִמֵּעַ֖יִךְ יִפָּרֵ֑דוּ וּלְאֹם֙ מִלְאֹ֣ם יֶֽאֱמָ֔ץ וְרַ֖ב יַעֲבֹ֥ד צָעִֽיר׃ (כד) וַיִּמְלְא֥וּ יָמֶ֖יהָ לָלֶ֑דֶת וְהִנֵּ֥ה תוֹמִ֖ם בְּבִטְנָֽהּ׃ (כה) וַיֵּצֵ֤א הָרִאשׁוֹן֙ אַדְמוֹנִ֔י כֻּלּ֖וֹ כְּאַדֶּ֣רֶת שֵׂעָ֑ר וַיִּקְרְא֥וּ שְׁמ֖וֹ עֵשָֽׂו׃ (כו) וְאַֽחֲרֵי־כֵ֞ן יָצָ֣א אָחִ֗יו וְיָד֤וֹ אֹחֶ֙זֶת֙ בַּעֲקֵ֣ב עֵשָׂ֔ו וַיִּקְרָ֥א שְׁמ֖וֹ יַעֲקֹ֑ב וְיִצְחָ֛ק בֶּן־שִׁשִּׁ֥ים שָׁנָ֖ה בְּלֶ֥דֶת אֹתָֽם׃ (כז) וַֽיִּגְדְּלוּ֙ הַנְּעָרִ֔ים וַיְהִ֣י עֵשָׂ֗ו אִ֛ישׁ יֹדֵ֥עַ צַ֖יִד אִ֣ישׁ שָׂדֶ֑ה וְיַעֲקֹב֙ אִ֣ישׁ תָּ֔ם יֹשֵׁ֖ב אֹהָלִֽים׃
(22) But the children struggled in her womb, and she said, “If so, why do I exist?” She went to inquire of the LORD, (23) and the LORD answered her, “Two nations are in your womb, Two separate peoples shall issue from your body; One people shall be mightier than the other, And the older shall serve the younger.” (24) When her time to give birth was at hand, there were twins in her womb. (25) The first one emerged red, like a hairy mantle all over; so they named him Esau. (26) Then his brother emerged, holding on to the heel of Esau; so they named him Jacob. Isaac was sixty years old when they were born. (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.
ויתרוצצו. עַ"כָּ הַמִּקְרָא הַזֶּה אוֹמֵר דָּרְשֵׁנִי, שֶׁסָּתַם מַה הִיא רְצִיצָה זוֹ וְכָתַב אִם כֵּן לָמָּה זֶּה אָנֹכִי? רַבּוֹתֵינוּ דְּרָשׁוּהוּ לְשׁוֹן רִיצָה; כְּשֶׁהָיְתָה עוֹבֶרֶת עַל פִּתְחֵי תּוֹרָה שֶׁל שֵׁם וָעֵבֶר יַעֲקֹב רָץ וּמְפַרְכֵּס לָצֵאת, עוֹבֶרֶת עַל פֶּתַח עֲבוֹדַת אֱלִילִים, עֵשָׂו מְפַרְכֵּס לָצֵאת. דָּבָר אַחֵר מִתְרוֹצְצִים זֶה עִם זֶה וּמְרִיבִים בְּנַחֲלַת שְׁנֵי עוֹלָמוֹת.
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).
ויגדלו הנערים. פירש"י כל זמן שהיו קטנים לא היו מעשיהן נכרין כיון שנעשו בני י"ג שנה זה פירש לבית המדרש וזה פירש לע"ז משל לנעצוצית והדס שהן גדלין זה עם זה כל זמן שהם קטנים אין אדם מבחין בין זה לזה הגדילו זה ריחו וזה חוחו ב"ר. ואי קשיא דפרש"י שעשו לא היה כי אם בן י"ג שנה כשפירש לע"ז שהרי הוא עצמו פי' ויזד יעקב נזיד שאותו יום מת אברהם שלא יראה עשו בן בנו יוצא לתרבות רעה וזהו שיבה טובה שהבטיחו הקב"ה. ולפי זה שאמרנו שהוא בן י"ג שנה א"כ מרד בחיי אברהם ב' שנים שהרי אברהם חי קע"ה שנה ובן מאה שנה היה כשנולד יצחק ויצחק בן ששים שנה כשנולד עשו ומשם עד קע"ה יש ט"ו שנים מכלל שהיה עשו בן ט"ו שנים כשמת אברהם א"כ מרד שתי שנים בחייו. בירושלמי פריך לה הכי ומשני שנתים מרד במטמוניות פי' בצנעה אבל לאחר מותו מרד בפרהסיא:

ויגדלו הנערים, “the lads grew up;” according to Rashi and the Midrash, as long as the twins had not attained the age of 13 one could not tell their characters apart. As soon as they reached that age it became evident that they pursued totally different objectives in life. The matter can be compared to thorn bushes growing up next to myrtles. Until they have developed, they look alike and neither emits any fragrance. After a while, the fragrance emitted from the myrtle distinguishes it drastically from the thorns of the thorn bushes. You might question that according to Rashi, Esau was only thirteen years old when he already chose to worship idols, while the same Rashi claims that when Esau sold his birthright he was `15 years old on the day of Avraham’s burial, and he claims that Avraham died five years earlier than originally decreed by God to spare him watching his grandson become an idolater; how can these two statements be reconciled, if Esau became an idolater already at the age of thirteen? This question has actually been raised in the Jerusalem Talmud! The answer given there is that Esau hid his idolatry for two years so that during the last two years of his life, Avraham had not become aware and grieved by it. As soon as Avraham died, Esau no longer hid the fact that he had become a heretic.

ויצא הראשון אדמוני. מדרש כשראהו אביו אמר עדיין לא נבלע בו דמיו ולא רצה למולו לשמונה ימים כדאמרינן גבי מעשה דשתי נשים שבאו לפני נתן הבבלי וכו'. כשעבר שנה או שנתיים וראה יצחק שלא החליף מראיתו ידע שזו תולדתו ואפ"ה לא מל אותו אמר הואיל ולא מלתי אותו לשמנה כמוני אמתין עד שיהיה בן י"ג כמו ישמעאל אחי ואמול אותו וכשהיה בן י"ג שנה הוא עכב בעצמו ולא רצה למול והיינו דכתיב אם לא דם שנאת ודם ירדפך:
ויצא הראשון אדמוני, “the first baby emerged, reddish looking;” according to a Midrash, when his father saw that, he concluded that the blood of the infant had not yet matured to the stage when he could be circumcised without that operation endangering his life, and that is why he delayed the date for the circumcision. Something similar is related in the Talmud, tractate Shabbat, folio 134, where Rabbi Nathan relates that he once met a lady who had lost two of her children as a result of circumcision. She asked him if she had to circumcise her third son also and risk losing him too. When Rabbi Nathan looked at the infant, he noted that his skin looked extremely red. He therefore told his mother to wait with circumcising him until this red skin would become normal looking. She did so, and circumcised him in due course and he survived without further problem. When Yitzchok waited a year or two for the skin colour of Esau to change and it did not happen, he assumed that this son was going to remain in that condition, but he still did not circumcise him. When he turned 13, he still restrained himself from circumcising him. He had waited all this time thinking that seeing he had not been circumcised at the age of eight days he would circumcise him at the age Yishmael had been circumcised. This is what was meant in the Book of Ezekiel chapter 35,6: אם לא דם שנאת ודם ירדפך, “surely though you have hated blood, blood shall pursue you.”
דבר אחר שלא מרד עשו בימיו דבר אחר שעשה ישמעאל תשובה בימיו שלא מרד עשו בימיו מנלן דכתיב (בראשית כה, כט) ויבא עשו מן השדה והוא עיף ותנא אותו היום נפטר אברהם אבינו ועשה יעקב אבינו תבשיל של עדשים לנחם את יצחק אביו
Alternatively, what is the blessing of bakkol? That Esau did not rebel in Abraham’s lifetime, that is to say, as long as Abraham lived Esau did not sin. Alternatively, the blessing of bakkol is that Ishmael repented in Abraham’s lifetime. The Gemara explains: From where do we derive that Esau did not rebel in Abraham’s lifetime? As it is written: “And Jacob was cooking a stew and Esau came in from the field and he was faint” (Genesis 25:29), and a baraita taught: On that day Abraham our forefather passed away, and Jacob our forefather prepared a lentil stew to comfort Isaac, his father, as it was customary to serve mourners lentil stew.
אמר רבי יוחנן חמש עבירות עבר אותו רשע באותו היום בא על נערה מאורסה והרג את הנפש וכפר בעיקר וכפר בתחיית המתים ושט את הבכורה
Rabbi Yoḥanan says: That wicked Esau committed five transgressions on that day that Abraham died: He engaged in sexual intercourse with a betrothed maiden, he killed a person, he denied the principle of God’s existence, he denied resurrection of the dead, and he despised the birthright.
ושעשה ישמעאל תשובה בימיו מנלן כי הא דרבינא ורב חמא בר בוזי הוו יתבי קמיה דרבא וקא מנמנם רבא א"ל רבינא לרב חמא בר בוזי ודאי דאמריתו כל מיתה שיש בה גויעה זו היא מיתתן של צדיקים אמר ליה אין והא דור המבול אמר ליה אנן גויעה ואסיפה קאמרינן והא ישמעאל דכתיב ביה גויעה ואסיפה אדהכי איתער בהו רבא אמר להו דרדקי הכי א"ר יוחנן ישמעאל עשה תשובה בחיי אביו שנאמר (בראשית כה, ט) ויקברו אותו יצחק וישמעאל בניו ודילמא דרך חכמתן קא חשיב להו אלא מעתה (בראשית לה, כט) ויקברו אותו עשו ויעקב בניו מאי טעמא לא חשיב להו דרך חכמתן אלא מדאקדמיה אדבורי אדבריה ומדאדבריה שמע מינה תשובה עבד בימיו
And from where do we derive that Ishmael repented in Abraham’s lifetime? From the incident involving Ravina and Rav Ḥama bar Buzi, who were sitting before Rava, and Rava was dozing while they were talking. Ravina said to Rav Ḥama bar Buzi: Is it true that you say that any death with regard to which the word gevia, expire, is mentioned is the death of the righteous? Rav Ḥama bar Buzi said to him: Yes. For example: “And Isaac expired [vayyigva], and died” (Genesis 35:29). Ravina objected: But with regard to the generation of the flood it states: “And all flesh expired [vayyigva]” (Genesis 7:21), and there they died for their wickedness. Rav Ḥama bar Buzi said to him: We say this only when both gevia and asifa, gathering, are used; when these two terms are mentioned together they indicate the death of a righteous person. Ravina asked: But isn’t there Ishmael, about whom gevia and asifa are written, as it is stated: “And these are the years of the life of Yishmael…and he expired and died [vayyigva vayyamot]; and was gathered to his people” (Genesis 25:17)? Meanwhile Rava, who had heard the discussion in his dozed state, fully awoke and said to them: Children [dardekei], this is what Rabbi Yoḥanan says: Ishmael repented in the lifetime of his father, as it is stated: “And Isaac and Ishmael, his sons, buried him” (Genesis 25:9). The fact that Ishmael allowed Isaac to precede him demonstrates that he had repented and accepted his authority. The Gemara asks: But perhaps the verse listed them in the order of their wisdom; that is to say, perhaps in fact Ishmael preceded Isaac but the Torah did not list them in that order. The Gemara answers: But if that is so, consider that the verse states: “And Esau and Jacob, his sons, buried him” (Genesis 35:29). What is the reason that the verse there did not list them in the order of their wisdom? Rather, since Ishmael allowed Isaac to precede him, it is clear that he made Isaac his leader, and since he made him his leader, learn from it that he repented in Abraham’s lifetime.
(כח) וְיִֽתֶּן־לְךָ֙ הָאֱלֹהִ֔ים מִטַּל֙ הַשָּׁמַ֔יִם וּמִשְׁמַנֵּ֖י הָאָ֑רֶץ וְרֹ֥ב דָּגָ֖ן וְתִירֹֽשׁ׃
(28) “May God give you Of the dew of heaven and the fat of the earth, Abundance of new grain and wine.
(ג) האלהים. מַהוּ הָאֱלֹהִים? בַּדִּין; אִם רָאוּי לְךָ יִתֵּן לְךָ וְאִם לָאו לֹא יִתֵּן לְךָ, אֲבָל לְעֵשָׂו אָמַר מִשְׁמַנֵּי הָאָרֶץ יִהְיֶה מוֹשָׁבֶךָ, בֵּין צַדִּיק בֵּין רָשָׁע יִתֵּן לְךָ; וּמִמֶּנּוּ לָמַד שְׁלֹמֹה, כְּשֶׁעָשָׂה הַבַּיִת סִדֵּר תְּפִלָּתוֹ. יִשְׂרָאֵל שֶׁהוּא בַעַל אֱמוּנָה וּמַצְדִּיק עָלָיו אֶת הַדִּין לֹא יִקְרָא עָלֶיךָ תִּגָּר, לְפִיכָךְ וְנָתַתָּ לָאִישׁ בְכָל דְּרָכָיו אֲשֶׁר תֵּדַע אֶת לְבָבוֹ (מלכים א, ח'), אֲבָל נָכְרִי מְחֻסַּר אֲמָנָה, לְפִיכָךְ אָמַר אַתָּה תִּשְׁמַע הַשָּׁמַיִם, וְעָשִׂיתָ כְּכֹל אֲשֶׁר יִקְרָא אֵלֶיךָ הַנָּכְרִי (שם), בֵּין רָאוּי בֵּין שֶׁאֵינוֹ רָאוּי תֵּן לוֹ, כְּדֵי שֶׁלֹּא יִקְרָא עָלֶיךָ תִּגָּר:
(3) האלהים GOD [GIVE THEE]—What denotes the use here of the Divine Name אלהים which signifies God in His attribute of Justice? May He act in justice! If you are worthy of it may He give it to you, and if not, let Him not give it to you. But to Esau he said, (Genesis 27:39) “The fat places of the earth shall be thy dwelling” —whether you be righteous or wicked He will give you this. From him (Isaac) did Solomon learn when he built the Temple how to compose his prayer (having in mind a similar idea): An Israelite who is a man of faith and acknowledges that God’s judgment is just will not reproach You;—therefore (1 Kings 8:39) “Render unto every man (Israelite; 1 Kings 8:38) according to his ways whose heart thou knowest”. A stranger, however, is lacking in faith; therefore Solomon said, (1 Kings 8:43) “Hear thou in heaven … and do according to all that the stranger calleth to thee for — whether he be worthy or unworthy grant him his request in order that he may not reproach You. This explanation of האלהים is found in an old and correct text of Rashi.
(משלי ב, יט) כל באיה לא ישובון ולא ישיגו אורחות חיים וכי מאחר שלא שבו היכן ישיגו ה"ק ואם ישובו לא ישיגו אורחות חיים
The following verse in Proverbs makes reference to a foreign woman, which according to the Sages is a euphemism for heresy: “None that go to her return, neither do they attain the paths of life” (Proverbs 2:19). The Gemara asks: Since those that are drawn to heresy do not return, from where would they attain the path of life? Why is it necessary for the verse to add that they do not attain the paths of life? The Gemara explains that this is what the verse is saying: In general, those who go to her do not return, and even if they return, they do not attain the paths of life, i.e., the pain of their regret will shorten their lives.
(לז) וַיַּ֨עַן יִצְחָ֜ק וַיֹּ֣אמֶר לְעֵשָׂ֗ו הֵ֣ן גְּבִ֞יר שַׂמְתִּ֥יו לָךְ֙ וְאֶת־כָּל־אֶחָ֗יו נָתַ֤תִּי לוֹ֙ לַעֲבָדִ֔ים וְדָגָ֥ן וְתִירֹ֖שׁ סְמַכְתִּ֑יו וּלְכָ֣ה אֵפ֔וֹא מָ֥ה אֶֽעֱשֶׂ֖ה בְּנִֽי׃ (לח) וַיֹּ֨אמֶר עֵשָׂ֜ו אֶל־אָבִ֗יו הַֽבְרָכָ֨ה אַחַ֤ת הִֽוא־לְךָ֙ אָבִ֔י בָּרֲכֵ֥נִי גַם־אָ֖נִי אָבִ֑י וַיִּשָּׂ֥א עֵשָׂ֛ו קֹל֖וֹ וַיֵּֽבְךְּ׃ (לט) וַיַּ֛עַן יִצְחָ֥ק אָבִ֖יו וַיֹּ֣אמֶר אֵלָ֑יו הִנֵּ֞ה מִשְׁמַנֵּ֤י הָאָ֙רֶץ֙ יִהְיֶ֣ה מֽוֹשָׁבֶ֔ךָ וּמִטַּ֥ל הַשָּׁמַ֖יִם מֵעָֽל׃ (מ) וְעַל־חַרְבְּךָ֣ תִֽחְיֶ֔ה וְאֶת־אָחִ֖יךָ תַּעֲבֹ֑ד וְהָיָה֙ כַּאֲשֶׁ֣ר תָּרִ֔יד וּפָרַקְתָּ֥ עֻלּ֖וֹ מֵעַ֥ל צַוָּארֶֽךָ׃
(37) Isaac answered, saying to Esau, “But I have made him master over you: I have given him all his brothers for servants, and sustained him with grain and wine. What, then, can I still do for you, my son?” (38) And Esau said to his father, “Have you but one blessing, Father? Bless me too, Father!” And Esau wept aloud. (39) And his father Isaac answered, saying to him, “See, your abode shall enjoy the fat of the earth And the dew of heaven above. (40) Yet by your sword you shall live, And you shall serve your brother; But when you grow restive, You shall break his yoke from your neck.”