John Gill Commentary Jeremiah 11:3

"and say thou unto them, Thus saith Jehovah, the God of Israel: Cursed be the man that heareth not the words of this covenant," — Jeremiah 11:3 (ASV)

And say thou unto them
This shows that the command of publishing the law or covenant was, however, principally given to Jeremiah: thus says the Lord, the God of Israel ;
that made them, and brought them out of Egypt, and made a covenant with them, and had taken care of them, and had bestowed many favours upon them: cursed be the man that obeys not the words of this covenant ;
which the prophet, it may be, had in his hands, even the book of the law, and held it forth unto them, while he was speaking; the language of which is, cursed is everyone that does not constantly and perfectly perform what is contained in it, (Deuteronomy 27:26) .