Jeremiah 34:13-16
34:13 “The Lord God of Israel has a message for you. ‘I made a covenant with your ancestors when I brought them out of Egypt where they had been slaves. It stipulated,
34:14 “Every seven years each of you must free any fellow Hebrews who have sold themselves to you. After they have served you for six years, you shall set them free.” But your ancestors did not obey me or pay any attention to me.
34:15 Recently, however, you yourselves showed a change of heart and did what is pleasing to me. You granted your fellow countrymen their freedom and you made a covenant to that effect in my presence in the house that I have claimed for my own.
34:16 But then you turned right around and showed that you did not honor me. Each of you took back your male and female slaves whom you had freed as they desired, and you forced them to be your slaves again.