Devarim 21:12

ועשת את צפרניה means, AND SHE SHALL LET GROW HER NAILS — She must let them grow, so that she should becomes repulsive to her captor (cf. Sifrei Devarim 212:4; Yevamot 48a; see also Rashi on Genesis 1:7 and our Note thereon).

וַהֲבֵאתָ֖הּ אֶל־תּ֣וֹךְ בֵּיתֶ֑ךָ וְגִלְּחָה֙ אֶת־רֹאשָׁ֔הּ וְעָשְׂתָ֖ה אֶת־צִפׇּרְנֶֽיהָ׃

then thou shalt bring her home to thy house; and she shall shave her head, and pare her nails;