Jeremiah 35:12 - Ellicott's Commentary On The Whole Bible

Then came the word of the Lord unto Jeremiah. — Up to this time the prophet had acted on the thought which came into his mind as an inspiration, without apparently more than a partial insight into its meaning. Now, as the words indicate, he passes at once into the prophetic state and speaks the prophetic words. It follows from Jeremiah 35:18 that it was uttered in the presence of the Rechabites and formed, we may believe, the conclusion of this strange dramatic scene.