"And the sons of God saw" (Genesis 6:2). [This means] the sons of judges. Every breach that does not come from the great ones is no breach; [as the proverb says,] the priests steal the god, by what shall one swear, or to whom shall one draw near? And why does Scripture call them "sons of God"? Because they prolonged their days without trouble and without suffering. And why so much ease? In order that they might observe the seasons and the constellations, and so that they might receive their portion and the portion of the generations that came after them. Rabbi Shimon bar Yochai would curse anyone who called them "sons of God." "That they were fair [tovot]." It is written tovat [in the construct], [teaching] that when they were beautifying a woman for her husband, the greatest among them would enter and lie with her first. "That they were fair": these are the unmarried women. "And they took for themselves wives": these are the wives of other men. "Of all that they chose": this refers to males and to beasts. And they were not blotted out from the world until they wrote marriage contracts for males and for beasts. In every place where you find fornication, mass destruction comes into the world and slays the good and the wicked alike. Over everything the Holy One, blessed be He, is long-suffering, except for fornication. What is the reason? "And they took for themselves wives of all that they chose," and it is written after it, "And the LORD said, I will blot out man" (Genesis 6:7).
The Sons of the Judges and the Corruption That Doomed the Generation
Yalkut Shimoni on Torah 43:4
(בראשית ו ב) וַיִּרְאוּ בְנֵי הָאֱלֹהִים. בְּנֵי דַּיָּנָא כָּל פִּרְצָה שֶׁאֵינָהּ מִן הַגְּדוֹלִים אֵינָהּ פִּרְצָה כֻּמְרַיָא גַּנְבִין אֱלָהָא מַאן מוּמֵי בֵּיהּ, אוֹ מַאן מִקְרָב, וְלָמָּה הוּא קוֹרֵא אוֹתָן בְנֵי הָאֱלֹהִים, שֶׁהִרְבּוּ יָמִים בְּלֹא צַעַר וּבְלֹא יִסּוּרִין, וְכָל כָּךְ לָמָּה, כְּדֵי לַעֲמֹד עַל הַתְּקוּפוֹת וְעַל הַמַּזָּלוֹת וּכְדֵי שֶׁיִּטְּלוּ אֶת שֶׁלָּהֶן וְשֶׁל דּוֹרוֹת הַבָּאִין אַחֲרֵיהֶן רַבִּי שִׁמְעוֹן בַּר יוֹחָאי מְקַלֵּל לְכָל מַאן דְּקָרֵי לְהוֹן בְּנֵי אֱלָהָא כִּי טֹבֹת הֵנָּה. טָבַת כְּתִיב מִשֶּׁהָיוּ מֵטִיבִין אִשָּׁה לְבַעֲלָהּ הַגָּדוֹל מֵהֶן נִכְנָס וּבוֹעֲלָהּ תְּחִלָּה. כִּי טֹבֹת הֵנָּה, אֵלּוּ הַפְּנוּיוֹת, וַיִּקְחוּ לָהֶם נָשִׁים, אֵלּוּ נְשֵׁי אֲנָשִׁים. מִכֹּל אֲשֶׁר בָּחָרוּ, זֶה זָכוּר וּבְהֵמָה. וְלֹא נִמְחוּ מִן הָעוֹלָם עַד שֶׁכָּתְבוּ גְמַמְסִיוֹת לַזָּכוּר וְלַבְּהֵמָה. בְּכָל מָקוֹם שֶׁאַתְּ מוֹצֵא זְנוּת, אַנְדְרַלָמוּסְיָא בָּאָה לָעוֹלָם וְהוֹרֶגֶת הַטּוֹבִים וְהָרָעִים. עַל הַכֹּל הַקָּדוֹשׁ בָּרוּךְ הוּא מַאֲרִיךְ אַפּוֹ חוּץ מִן הַזְּנוּת. מַה טַעַם, וַיִּקְחוּ לָהֶם נָשִׁים מִכֹּל אֲשֶׁר בָּחָרוּ, וּכְתִיב בַּתְרֵיהּ וַיֹּאמֶר ה' אֶמְחֶה אֶת הָאָדָם.