Jeremiah 34:13-14

13‘The Lord, Israel's God, says this to the people: I made a covenant with your ancestors when I brought them out of Egypt. They had been slaves when they were there.

14I told them, “When any Hebrew slave has worked for you for six years, you must let them go free. In the seventh year after they sold themselves to you, you must set them free.” But your ancestors did not listen to me. They did not obey me.