Then took they Jeremiah, and cast him into the dungeon of Malchiah the son of Hammelech, that was in the court of the prison: and they let down Jeremiah with cords. And in the dungeon there was no water, but mire: so Jeremiah sunk in the mire.
Then took they Jeremiah, and cast him into the dungeon - literally, the cistern of Malchiah. It was not a subterranean prison, as was that in Jonathan's house (Jeremiah 37:15), but a pit or cistern which had been full of water, but was emptied of it during the siege, so that only "mire" remained. Such empty cisterns were often used as prisons (Zechariah 9:11, "By the blood of thy covenant I have sent forth thy prisoners out of the pit wherein is no water"); the depth forbade hope of escape.
Malchiah the son of Hammelech - (see note, Jeremiah 36:26). Like Jerahmeel his brother, Malchiah, who was also "the son of Hammelech," was a ready tool for evil.
So Jeremiah sunk in the mire. Jeremiah herein was a type of Messiah, (Psalms 69:2; Psalms 69:14, "I sink in deep mire," etc.)