וַתֵּצֵ֤א דִינָה֙ בַּת־לֵאָ֔ה אֲשֶׁ֥ר יָלְדָ֖ה לְיַעֲקֹ֑ב לִרְא֖וֹת בִּבְנ֥וֹת הָאָֽרֶץ׃
And Dinah the daughter of Leah, whom she had borne to Yaakov, went out to see the daughters of the land.
Rashi on Bereishis 34:1, citing Bereshit Rabbah 80:1.
Sefaria · Rashi on Genesis 34:1
בַּת לֵאָה — וְלֹא בַת יַעֲקֹב? אֶלָּא עַל שֵׁם יְצִיאָתָהּ נִקְרֵאת בַּת לֵאָה, שֶׁאַף הִיא יוֹצְאָנִית הָיְתָה, שֶׁנֶּאֱמַר וַתֵּצֵא לֵאָה לִקְרָאתוֹ.
“The daughter of Leah” — why not the daughter of Yaakov? She is called Leah’s daughter because of her going out; Leah too was associated with “going out,” as it says, “And Leah went out to meet him.”
Rashi explains the unusual identification of Dinah as Leah’s daughter through the Midrash’s comparison between mother and daughter.
Classical commentary with a Midrashic source (Rashi / Bereshit Rabbah).
The wording “daughter of Leah” is read as an interpretive clue to the circumstances of Dinah’s going out.