"You shall not give back to his master the slave who has escaped from his master to you.
Deuteronomy 23:15
Surrounding context
23:14 For the LORD your God walks in the midst of your camp, to deliver you and give your enemies over to you; therefore your camp shall be holy, that He may see no unclean thing among you, and turn away from you.
23:15 "You shall not give back to his master the slave who has escaped from his master to you.
23:16 He may dwell with you in your midst, in the place which he chooses within one of your gates, where it seems best to him; you shall not oppress him.