After ten years of infertility, in which Yitzchak and Rivka poured their hearts out in prayer for children, their prayers were finally answered and Rivka conceived. In truth, Rivka was barren, and it was physically impossible for her to have children. Hashem answered their prayers with a miracle that transcended nature. One would think that her joy would be so overwhelming that nothing could diminish it. Yet when it seemed that her unborn child was inclined towards idolatry, she regretted her prayers, as we find in this week’s parsha:
ויתרצצו הבנים בקרבה ותאמר אם כן למה זה אנכי.
“The children struggled within her, and she said, ‘If so, why did I pray for this?’”
Rashi explains that when Rivka passed by the entrance to Shem’s Torah school, Yaakov struggled in his enthusiasm to go study Torah. When she passed by the entrance to idolatrous temples, Eisav struggled in his enthusiasm to go worship idols.
She was sorely troubled by the thought that her child’s heart was split between Torah study idolatry. How then was she appeased when she was informed that she carried twins – one of whom would be perfectly righteous, while the other would be wicked?
When the Avos and Imahos prayed for children, they did not seek their own personal pleasure. Their prayers were solely for the sake of Heaven – to bring a new generation into the world who would toil in the service of Hashem, through Torah study and mitzva observance. Their intention was solely to plant an orchard, from which holy saplings would grow. When it seemed to Rivka that she was carrying one child who was attracted both to Torah study and idolatry, she realized that this could not possibly be the scion for which she had hoped, and therefore regretted all her prayers. Only after Shem informed her that she carried twins, only one of whom would be wicked while the other would be perfectly righteous, was she satisfied with the knowledge that her aspirations would be fulfilled through Yaakov.
The Midrash states as follows:
רבי יודן ורבי אייבו בשם רבי יוחנן שני בני אדם אמרו דבר אחד, אברהם ודוד. אברהם כתיב ביה "ה' אלהים מה תתן לי" - אמר לפניו "רבונו של עולם אם עתיד אני להעמיד בנים ולהכעיסך מוטב לי ואני הולך ערירי." דוד אמר "חקרני אל ודע לבבי", דע הפורשים ממני "וראה אם דרך עצב בי ונחני בדרך עולם" - אמר לפניו "רבונו דל עולם אם עתיד אני להעמיד בנים להעציבך מוטב לי ונחני בדרך עולם."
Rebbe Yuden and Rebbe Aibo said in the name of Rebbe Yochanan: Avraham and David both prayed for the same thing. Avraham prayed, “Hashem Elokim, what could You give me if I remain desolate without children?” He meant to say, “Master of the Universe, If I will father children who will anger You, it is better that I remain desolate.”
David also prayed, “Search me, Lord, and know my heart” – look towards those who I am destined to father, “See if the path of anger is before me, and guide me in the way of the world.” He meant to say, “Master of the Universe, If I will father children who will anger You, it is better that You guide me in the way of the world (towards death).”
Avraham and David, the pillars of our nation, preferred to remain childless rather than bring children into the world who might anger Hashem. Rivka’s sentiments were the same.
We find in the Mishna that a father passes on to his son the physical properties of beauty (נוי), strength (כח), and wisdom (חכמה). Some explain that when Yitzchak prayed for children “across from” (לנכח) his wife, he was really praying for a child who would have all three of these properties, the first letters of which spell the word נכח. However, when Rivka passed by the entrance to idolatrous temples and felt her unborn child struggling to escape, she asked, "למה כן אנכי", “Why did I pray for this?” The first letters of כן stand for כח (strength) and נוי (beauty). She did not want a strong and beautiful baby, if he would not grow to become wise in the wisdom of the Torah.
In the Shlah’s prayer for children, customarily recited on the day before Rosh Chodesh Sivan, he writes that the two mitzvos of Torah study and pru u’rvu (“be fruitful and multiply”) are both directed towards the same purpose:
על הקיום העולם ועל קיום התורה בא לנו ממך ה' אלוקינו שני צוויים. כתבת בתורתך פרו ורבו, וכתכת בתורתך ולמדתם אותם את בניכם, והכונה בשניהם אחת כי לא לתהו בראת כי אם לשבת, ולכבודך בראת יצרת אף עשית, כדי שנהיה אנחנו וצאצאינו וצאצאי כל עמך בית ישראל יודעי שמך ולומדי תורתך.
For the preservation of the world and the preservation of the Torah we have received from You, Hashem our G‑d, two commandments. You wrote in Your Torah, “Be fruitful and multiply,” and You wrote in Your Torah, “You shall teach it to your children.” The purpose of both mitzvos is as one; You did not create the world to lie fallow, but to be settled. For the sake of Your honor You created, formed and fashioned it, so that we and our descendants and the descendants of Your entire nation, the House of Israel, shall all know Your Name and study Your Torah.
Thus the prayers of the Avos for children were not selfish prayers for their own nachas, but prayers for the sake of Heaven – so that their mission of sanctifying Hashem’s Name in the world could continue through their offspring even after they pass away. Their prayers were answered through Yaakov alone, and not through Eisav, for which reason Hashem told Avraham: כי ביצחק יקרא לך זרע – “For among Yitzchak shall your progeny be called.”
The word ביצחק, as opposed to יצחק, implies that only some of Yitzchak’s descendants would be considered Avraham’s spiritual progeny. Yaakov alone carried the torch passed down by his forefathers, with which he illuminated the entire world with his Torah and mitzvos. He, and not Eisav, was the child for whom Rivka had prayed.
 Bereishis 25:22
 Bereishis 15:2
 Tehillim 139:24
 Bereishis Rabbah 44:9
 Eidiyos 2:9
 Bereishis 25:21
 Bereishis 21:12
 Nedarim 31a