Jeremiah 32:12

And I gave the evidence of the purchase unto Baruch the son of Neriah, the son of Maaseiah, in the sight of Hanameel mine uncle's son, and in the presence of the witnesses that subscribed the book of the purchase, before all the Jews that sat in the court of the prison.

Baruch - Jeremiah's amanuensis and agent, (, etc.)

Before all. In sales everything clandestine was avoided; publicity was required. So here, in the court of the prison where Jeremiah was confined, there were soldiers and others present, who had free access to him ().