Jamieson, Fausset and Brown on 2 Kings 25:27

27. seven and thirtieth year of the captivity of Jehoiachin--corresponding with the year of Nebuchadnezzar's death, and his son Evil-merodach's ascension to the throne.

Evil-merodach ... did lift up the head of Jehoiachin ... and spake kindly--gave him liberty upon parole. This kindly feeling is said to have originated in a familiar acquaintance formed in prison, in which Evil-merodach had lain till his father's death, on account of some malversation while acting as regent during Nebuchadnezzar's seven years' illness (Da 4:32, 33). But doubtless the improvement in Zedekiah's condition is to be traced to the overruling providence and grace of Him who still cherished purposes of love to the house of David (2Sa 7:14, 15).