Jeremiah 41:11
But when Johanan the son of Kareah, and all the captains of the forces that were with him, heard of all the evil that Ishmael the son of Nethaniah had done, But when Johanan the son of Kareah, and all the captains of the forces that were with him, heard of all the evil that Ishmael the son of Nethaniah had done,
Jeremiah 32 to 45 give the history of the two years before the fall of Jerusalem and include the prophecies uttered during the rule of Gedaliah. In chronological sequence this verse comes after Jeremiah 40 and before chapters 42-44, recording the events following the killing and other violence carried out by Ishmael. It marks the point when Johanan the son of Kareah and all the captains of the forces with him heard of the evil Ishmael the son of Nethaniah had done, as part of the account of events after Jerusalem's fall and destruction.
That evil was Ishmael's assassination and murder of Gedaliah at Mizpah, with his attack on the Jews remaining in Judah. Gedaliah was the Jewish viceroy left in the land by Nebuchadnezzar, the king of Babylon, after the destruction of Jerusalem. The attack scattered and dispersed the remnant of Jews who had been left and had gathered in Judah after Babylon had carried the nation away. These events prompted the fast observed in the seventh month, commemorated as the Fast of Gedaliah kept on Tisri 3 as one of the four fasts for the fall of Jerusalem, a fast beginning at daybreak.