This now seemed but a reasonable question, considering they were the substance of what he had been prophesying for so many years. The thing seemed strange to the princes, prophets being not used to study and pen their discourses, but to speak them extempore.
Related Commentaries of Jeremiah 36:17
Jeremiah 36:17
17 And they asked Baruch, saying, Tell us now, How didst thou write all these words at his mouth?