Jeremiah 34:12-14

For this reason the word of the Lord came to Jeremiah from the Lord, saying, The Lord, the God of Israel, has said, I made an agreement with your fathers on the day when I took them out of Egypt, out of the prison-house, saying, At the end of seven years every man is to let go his countryman who is a Hebrew, who has become yours for a price and has been your servant for six years; you are to let him go free: but your fathers gave no attention and did not give ear.