Jeremiah 5:12 - Ellicott's Commentary On The Whole Bible

It is not he. — i.e., It is not Jehovah who speaks. They listened to the prophet’s warnings as if they came from himself only, and brought with them no certainty of the “sword” or “famine” which they foretold. Perhaps, however, the words refer also to the denial that Jehovah was working in the sufferings that fell upon the people, or even to a more entire denial, like that of the fool in Psalms 14:1.