Jeremiah 34:10-11

And all the princes and all the people obeyed, that had entered into the covenant, that every one should let his man-servant, and every one his maid-servant, go free, that none should make bondmen of them any more; they obeyed, and let them go: but afterwards they turned, and caused the servants and the handmaids, whom they had let go free, to return, and brought them into subjection for servants and for handmaids.