Jeremiah 36:4

Then Jeremiah called Baruch the son of Neriah
One of his disciples, and whom he had before made use of in the purchase of a field of his uncle's son, and to whom he gave the evidence of the purchase, ( Jeremiah 32:12 ) ; he was probably a better penman than the prophet, or a quicker writer; however, he thought proper, for quicker dispatch, to make use of him as his amanuensis: and Baruch wrote from the mouth of Jeremiah all the words of the Lord,
which he had spoken unto him, upon a roll of a book;
it seems that Jeremiah had not committed any of his prophecies to writing; and yet it cannot be thought that by the mere strength of memory he could repeat every discourse and prophecy he had delivered in the space of two and twenty years; wherefore it must be concluded, that that same Spirit, which first dictated the prophecies to him, brought them fresh to his memory; so that he could readily repeat them to Baruch, who took them down in writing on a roll of parchment.