וְהֵסִ֩ירָה֩ אֶת־שִׂמְלַ֨ת שִׁבְיָ֜הּ מֵעָלֶ֗יהָ וְיָֽשְׁבָה֙ בְּבֵיתֶ֔ךָ וּבָֽכְתָ֛ה אֶת־אָבִ֥יהָ וְאֶת־אִמָּ֖הּ יֶ֣רַח יָמִ֑ים וְאַ֨חַר כֵּ֜ן תָּב֤וֹא אֵלֶ֙יהָ֙ וּבְעַלְתָּ֔הּ וְהָיְתָ֥ה לְךָ֖ לְאִשָּֽׁה׃
and she shall put the raiment of her captivity from off her, and shall remain in thy house, and bewail her father and her mother a full month; and after that thou mayest go in unto her, and be her husband, and she shall be thy wife.
Sifrei Devarim
(Devarim 21:13) "And she shall remove the garment of her captivity from her": We are hereby taught that he removes her alluring clothing and dresses her in widows' weeds; for the Canaanites would dress their daughters enticingly to cause others to stray after them.