(Devarim 23:16) "Do not deliver a servant to his master": From here they ruled: If one sells his servant to an idolator or to one outside of Eretz Yisrael, he goes free.
"who shall escape to you from his master": to include a ger toshav ("a sojourning stranger," a gentile who takes it upon himself not to serve idolatry and to heed the seen Noachide laws)
[If he leaves the gentiles and comes to Eretz Yisrael, do not return him to them.] (Ibid. 17) "With you shall he dwell" — in the city itself.
"in your midst" — and not in an outlying district. "in the place that he chooses" — where he can find sustenance.
"in your gates" — and not in Jerusalem. "in one of your gates" — and not in exile from city to city.
"where it is good for him" — from an inferior location to a superior one.
"you shall not oppress him" — verbal oppression.