Yevamot 63a
יבמות ס״ג א — ד"ה וְאָמַר רַבִּי אֶלְעָזָר
Yevamot 63a:5
The Gemara discusses the verse 'I will make for him a helper opposite him' and derives lessons about the uniqueness of woman as a fit counterpart to man. This sugya is part of the broader rabbinic background to the idea that Adam did not find a mate among the animals.
וְאָמַר רַבִּי אֶלְעָזָר, מַאי דִּכְתִיב: ״זֹאת הַפַּעַם עֶצֶם מֵעֲצָמַי וּבָשָׂר מִבְּשָׂרִי״ — מְלַמֵּד שֶׁבָּא אָדָם עַל כׇּל בְּהֵמָה וְחַיָּה, וְלֹא נִתְקָרְרָה דַּעְתּוֹ עַד שֶׁבָּא עַל חַוָּה.
And Rabbi Elazar said: What is the meaning of that which is written: “This is now bone of my bones and flesh of my flesh” (Genesis 2:23)? This teaches that Adam had intercourse with each animal and beast in his search for his mate, and his mind was not at ease, in accordance with the verse: “And for Adam, there was not found a helpmate for him” (Genesis 2:20), until he had intercourse with Eve.