Leviticus 21:3

הקרובה [AND FOR HIS SISTER A VIRGIN] THAT IS NIGH UNTO HIM — This is intended to include the sister who was only betrothed and has therefore not yet left her father's house and who is consequently still near to him (Sifra, Emor, Section 1 1; Yevamot 60a), for it continues אשר לא היתה לאיש, WHO HATH HAD NO HUSBAND — i. e. who has not yet entered into marital relations with him: לה יטמא — This is a command, [and the translation is: FOR HER HE SHALL DEFILE HIMSELF, not, “he may defile himself”] (Sifra, Emor, Section 1 12; Zevachim 100a).

וְלַאֲחֹת֤וֹ הַבְּתוּלָה֙ הַקְּרוֹבָ֣ה אֵלָ֔יו אֲשֶׁ֥ר לֹֽא־הָיְתָ֖ה לְאִ֑ישׁ לָ֖הּ יִטַּמָּֽא׃

and for his sister a virgin, that is near to him, and who has had no husband; for her may he be defiled.