Jeremiah 11:4 - Matthew Poole's English Annotations on the Holy Bible

Which I commanded your fathers, which law (that you by your restipulation made a formal covenant) I that am the Lord, and so had a sovereign power to lay laws upon my creatures, commanded your fathers, in the day that I brought them forth out of the land of Egypt, from the iron furnace; and obliged them to obedience before I laid my law upon them, by bringing them out of the land of Egypt, from the furnace wherein iron is melted, which may either be taken literally (probably that was a piece of their work in Egypt) or metaphorically, serving at iron furnaces being a very hard and servile labour. Saying, Obey my voice, and do them, according to all which I command you; for which kindness I required no more of them but a gentler service to me, in obeying my voice as to the things of this law which I gave them in charge. So shall ye be my people, and I will be your God; nor did I only lay my commands upon them, but I also encouraged them to the obedience of it, by my gracious promise, that if they would, they should be a people, I would bless, protect, and defend, and bear the name of my people, and I would be their God to own and bless them.