Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 232
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 232, with English translation by Maimonides (Rambam).
לדון בעבד עברי כהלכותיו, שנאמר: "כי תקנה עבד עברי" (שמות כא,ב).
To carry out the laws concerning a Hebrew servant, as [Exodus 21:2] states: "When you purchase a Hebrew servant...."