Charles Ellicott Commentary Jeremiah 4:14

"O Jerusalem, wash thy heart from wickedness, that thou mayest be saved. How long shall thine evil thoughts lodge within thee?" — Jeremiah 4:14 (ASV)

O Jerusalem. —The prophet’s answer to the cry that comes from the city. In that “washing of the heart,” which had seemed impossible before (Jeremiah 2:22), but is now thought of as “possible with God,” lies the one hope of salvation .

Vain thoughts. —The Hebrew has a force that the English does not reproduce: thoughts of vanity, thoughts of aven, i.e., of the word that had been specially applied, as in Beth-aven for Beth-el (the “house of vanity” for the “house of God”), to the idols that Israel and Judah worshipped (Hosea 4:15; Hosea 10:5; Amos 5:5).