Jeremiah 34:15-16

15And you, ye had this day turned, and had done right in my sight, in proclaiming liberty every man to his neighbour; and ye had made a covenant before me in the house which is called by my name:

16but ye have turned and profaned my name, and caused every man his bondman, and every man his bondmaid, whom ye had set at liberty at their pleasure, to return, and ye have brought them into subjection, to be unto you for bondmen and for bondmaids.