Jeremiah 34:13-14

13thus says Adonai, the God of Israel: “I made a covenant with your fathers in the day that I brought them out of the land of Egypt, out of the house of bondage, saying:

14‘At the end of seven years you are to set free every man his brother that is a Hebrew who has been sold to you and has served you six years; you are let him go free from you.’ But your fathers did not obey Me, nor inclined their ear.