Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 234
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 234, with English translation by Maimonides (Rambam).
לפדות אמה עברייה, שנאמר: "והפדה" (שמות כא,ח).
To redeem a Hebrew maidservant, as [Exodus, ibid.] states: "And she will be redeemed."