אִם־רָעָ֞ה בְּעֵינֵ֧י אֲדֹנֶ֛יהָ אֲשֶׁר־לא [ל֥וֹ] יְעָדָ֖הּ וְהֶפְדָּ֑הּ לְעַ֥ם נָכְרִ֛י לֹא־יִמְשֹׁ֥ל לְמָכְרָ֖הּ בְּבִגְדוֹ־בָֽהּ׃
Kung hindi siya kalugdan ng kanyang amo, na dapat sanang nagtakda sa kanya para sa sarili niya, hahayaan niyang matubos siya; wala siyang kapangyarihang ipagbili siya sa ibang tao, dahil sa pagtataksil niya sa kanya.
Sefer HaMitzvot
That is that He commanded us to redeem the Hebrew maidservant. And that is His, may He be blessed, saying, "he must let her be redeemed" (Exodus 21:8). This redemption has many analyses and conditions and there are many regulations for it - and they have been explained in Tractate Kiddushin. And the law of the Hebrew maidservant is completely explained there. And in the Mekhilta (Mekhilta d'Rabbi Yishmael 21:11:1) they said in explanation of, "And if these three he does not do to her" (Exodus 21:11), "Designate (marry) [her] yourself, to your son, or redeem her." (See Parashat Mishpatim; Mishneh Torah, Slaves 14.)