Jeremiah 34:10-11

10And all the princes and all the people that had entered into the covenant obeyed, every man letting his bondman and every man his bondmaid go free, that none should exact service of them any more: they obeyed, and let [them] go.

11But afterwards they turned, and caused the bondmen and the bondmaids whom they had let go free, to return, and brought them into subjection for bondmen and for bondmaids.