Jeremiah 34:13-16

13Thus saith the LORD, the God of Israel; I made a covenant with your fathers in the day that I brought them forth from the land of Egypt, out of the house of bondage, saying, 14At the end of seven years release ye every man his brother an Hebrew, who hath been sold to thee; and when he hath served thee six years, thou shalt let him go free from thee: but your fathers hearkened not to me, neither inclined their ear.1 15And ye had now 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:23 16But ye turned and profaned my name, and caused every man his male servant, and every man his female servant, whom he had set at liberty at their pleasure, to return, and brought them into subjection, to be to you for male and female servants.