זוהר, תולדות ג׳Zohar, Toldot 3

Segment 1א׳

פָּתַח רִבִּי יְהוּדָה אֲבַתְרֵיהּ וְאָמַר, (בראשית כ״ה:כ״א) וַיֶּעְתַּר יִצְחָק לַיְיָ לְנֹכַח אִשְׁתּוֹ. מַהוּ וַיֶּעְתַּר, דְּקָרִיב לֵיהּ קָרֵבָּנָא, וְצַלֵּי עֲלָהּ. וּמַה קָרְבָּנָא קָרִיב. עוֹלָה קָרִיב, דִּכְתִיב, (בראשית כ״ה:כ״א) וַיֵּעָתֶר לוֹ יְיָ, כְּתִיב הָכָא וַיֵּעָתֶר לוֹ יְיָ, וּכְתִיב הָתָם (שמואל ב כד) וַיֵּעָתֶר אֱלהִים לָאָרֶץ וְגו', מַה לְּהַלָּן קָרְבָּן אַף כָּאן קָרְבָּן. כְּתִיב וַיֶּעְתַּר יִצְחָק, וּכְתִיב וַיֵּעָתֶר לוֹ, דְּנָפַק אֶשָׁא מִלְּעֵילָא לְקֳבְלָא אֶשָׁא דִלְתַתָּא.

R. Judah followed with a discourse on the text: AND ISAAC ENTREATED THE LORD FOR HIS WIFE. ‘The term “entreated” (vaye’tar)’, he said, ‘implies prayer accompanied by offerings, on an analogy with a kindred term in the passage, “So the Lord was entreated for the land” (II Sam. 24, 25), where also the prayer was accompanied by offerings. It is written here first, “And Isaac entreated”, and then “And the Lord let himself be entreated”, indicating that a celestial fire descended to meet the fire ascending from below.

Segment 2ב׳

דָבָר אַחֵר, וַיֶּעְתַּר יִצְחָק. דְּצַלֵּי צְלוֹתֵיהּ, וְחָתַר חֲתִירָה לְעֵילָא לְגַבֵּי מַזָּלָא עַל בְּנִין, דְּהָא בְּהַהוּא אֲתַר תַּלְיָין בְּנִין, דִּכְתִיב, (שמואל א א׳:י׳) וַתִּתְפַּלֵּל עַל ה', וּכְדֵין וַיֵּעָתֶר לוֹ יְיָ, אַל תִּקְרֵי וַיֵּעָתֶר לוֹ אֶלָּא וַיֵּחָתֶר לוֹ, חֲתִירָה חָתַר לֵיהּ קוּדְשָׁא בְּרִיךְ הוּא, וְקַבִּיל לֵיהּ, וּכְדֵין וַתַּהַר רִבְקָה אִשְׁתּוֹ.

According to another explanation, the term vaye’tar (and he entreated) is akin to vayehtar (and he dug), signifying that Isaac in his prayer dug a tunnel, as it were, leading right up to the supernal department appointed over fecundity. He thus rose above the planetary influences (mazzal) in the same way as Hannah in her prayer, of whom it is written: “And she prayed unto (‘al’, lit. upon) the Lord” (I Sam. 1, 10) Similarly, the term vaye’ather (and he let himself be entreated) implies that the Lord Himself cleared a way for Isaac’s prayer, with the result that “Rebekah his wife conceived”.

Segment 3ג׳

תָּא חֲזֵי, עֶשְׂרִין שְׁנִין אִשְׁתָּהֵי יִצְחָק עִם אִתְּתֵיהּ וְלָא אוֹלִידַת, עַד דְּצַלֵּי צְלוֹתֵיהּ. בְּגִין דְּקוּדְשָׁא בְּרִיךְ הוּא אִתְרָעֵי בִּצְלוֹתְהוֹן דְּצַדִּיקַיָא, בְּשַׁעְתָּא דְּבָעָאן קַמֵּיהּ צְלוֹתְהוֹן עַל מַה דְּאִצְטְרִיכוּ. מַאי טַעְמָא, בְּגִין דְּיִתְרַבֵּי וְיִתּוֹסַף רְבוּת קוּדְשָׁא לְכָל מַאן דְּאִצְטְרִיךְ בִּצְלוֹתְהוֹן דְּצַדִּיקַיָּיא.

Observe that Isaac lived with his wife for twenty years without having children, the reason being that God delights in the prayer of the righteous, who thereby attain to higher sanctity and purification. He therefore withholds from them their needs until they offer their supplications.