וַיַּרְא־שָׁ֧ם יְהוּדָ֛ה בַּת־אִ֥ישׁ כְּנַעֲנִ֖י וּשְׁמ֣וֹ שׁ֑וּעַ וַיִּקָּחֶ֖הָ וַיָּבֹ֥א אֵלֶֽיהָ׃
유다가 거기서 가나안 사람 수아라 하는 자의 딸을 보고 그를 취하여 동침하니
Shenei Luchot HaBerit
וירא שם יודא בת איש כנעני . From this verse, our sages in Kidushin 41 derive the rule that one must not marry a woman until one has seen her.