Jeremiah 42:21

I have been faithful to you, I went according to your desire to inquire of God for you, I had his will revealed to me in your case, and now I have as faithfully told you what it is; but ye have not obeyed. How did Jeremiah know this, for they had not yet declared their minds to him? He had either learned it from their discourses during the ten days which God had made him to wait for the revelation, or he had learned it from some contemptuous behaviour of them when he delivered it, or (which is most probable) God had aforehand told it to him.