Jeremiah 34:10-11

So all the princes and all the people who had entered into the covenant agreed that everyone would let his male servant and his female servant go free, and that no one would keep them in bondage any longer; they obeyed, and set them free. But afterward they backed out [of the covenant] and made the male servants and the female servants whom they had set free return [to them], and brought the male servants and the female servants again into servitude.