Charles Ellicott Commentary Jeremiah 34:13

"Thus saith Jehovah, the God of Israel: I made a covenant with your fathers in the day that I brought them forth out of the land of Egypt, out of the house of bondage, saying," — Jeremiah 34:13 (ASV)

Thus saith the Lord ... —The prophet takes as his text the law which had been so flagrantly broken (Exodus 21:2), reminding them under what circumstances that law had been given. Their fathers had then been delivered from the house of bondage, and this was part of the covenant God had made with them—freedom and blessing being given by Him, and obedience promised by them. They were never to forget the bitterness of the bondage they had known (compare the form of the fourth commandment in Deuteronomy 5:15), and were to make it one of the fundamental laws of their national polity that no Israelite should ever pass, except by his own free choice, into a condition of hopeless, lifelong slavery.