John Calvin's Bible Commentary
Jeremiah 36:4
Here the Prophet declares that he dictated to Baruch, a servant of God, whatever he had previously taught. But there is no doubt but that God suggested to the Prophet at the time what might have been erazed from his memory; for all the things which we have some time ago said, do not always occur to us. Therefore the greater part of so many words must have escaped the Prophet, had not God dictated them again to him. Jeremiah then stood, as it were, between God and Baruch; for God, by his Spirit, presided over and guided the mind and tongue of the Prophet. Now the Prophet, the Spirit being his guide and teacher, recited what God had commanded; and Baruch wrote down, and then proclaimed the whole summary of what the Prophet had taught.
He therefore says, that he called to him Baruch the son of Neria, who wrote from his mouth, and he wrote all the words of Jehovah Jeremiah repeats again that nothing came from himself. We hence see that he did not dictate, according to his own will, what came to his mind, but that God suggested whatever he wished to be written by Baruch. It is added, that he commanded Baruch to recite in the Temple what he had written, because he himself was detained. Some think that he was shut up in prison; and he used the same word before, when he told us that he was cast into prison by Zedekiah. But as sacred history does not say that he suffered any such thing under Jehoiakim, I am inclined to think that he was prevented by God; I do not, however, ascribe it to a divine oracle; for it might have happened either through God’s command, or through some human impediments. (101) If we believe the Prophet to have been in prison, and that he might have gone out, he yet abstained; for the more liberty was given him, the more bound he felt himself to continue in prison, lest he should violate public authority. But the other supposition is more probable, that he was detained by God’s hand. However this may have been, he says that he could not go forth; and he mentioned this, lest it should appear that he was only careful as to himself, and that through fear of danger, he devolved this duty on Baruch. He then shews that he did not shun his office, because it exposed him to hatred, but that he was not at liberty to go forth.