(14) 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 thought of now as "possible with God," is the one hope of salvation. (Comp. Isaiah 1:16.)

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

Verse 14. - Thy vain thoughts. The phrase specially belongs to sins against one's neighbor - such sins as are described in Jeremiah 7:5-9 (Keil). "Vain" should rather be "wicked" (immoral); the root-meaning of the noun is "a breath" (the symbol of material or moral emptiness).

4:5-18 The fierce conqueror of the neighbouring nations was to make Judah desolate. The prophet was afflicted to see the people lulled into security by false prophets. The approach of the enemy is described. Some attention was paid in Jerusalem to outward reformation; but it was necessary that their hearts should be washed, in the exercise of true repentance and faith, from the love and pollution of sin. When lesser calamities do not rouse sinners and reform nations, sentence will be given against them. The Lord's voice declares that misery is approaching, especially against wicked professors of the gospel; when it overtakes them, it will be plainly seen that the fruit of wickedness is bitter, and the end is fatal.O Jerusalem, wash thine heart from wickedness,.... These are the words of the prophet, or of God by the prophet, showing the cause of all their ruin and destruction, the wickedness of their hearts; and they are expressed in such form and language, as to be accommodated to the case of any unregenerate sinner: every man's heart is wicked, desperately wicked, even wickedness itself; everything in it is wicked; the thoughts, and the imagination of the thoughts of the heart, the mind, the understanding, the will, the conscience, and the affections; and everything that is wicked is in that: it is the womb in which all sin is conceived; the shop and forge in which it is wrought; it is the habitation of every unclean lust; the seeds and principles of all sin are in it; it is the fountain spring and source of all evil; of all evil thoughts, words, and actions; all come out of it, and have their rise in it: and this wickedness is of a defiling nature, and has left a pollution on it; and what comes out of it defiles the man, that he stands in need of washing; which cannot be done to purpose by ceremonial ablutions and sacrifices, by moral acts of righteousness, by humiliation and tears, nor by submission to Gospel ordinances; nor indeed is this to be done by man at all, any other way than by faith dealing with the blood of Christ, by which only the heart is purified: for this is God's work, as appears from his promises to cleanse his people from all sins; from their prayers to him, to create in them clean hearts, to wash them thoroughly from their iniquity, and cleanse them from their sin; from the sanctifying grace of the Spirit, and the washing of regeneration ascribed to him; and from the end and efficacy of the bloodshed of Christ, to cleanse from sin, and purge the conscience from dead works; and the design of such exhortations as these is to convince men of the wickedness and pollution of their hearts, of the necessity of being washed from it, and of their own inability to do it of themselves; and to lead them to the fountain of Christ's blood, to wash in for sin and for uncleanness:

that thou mayest be saved; not only with a temporal salvation, which may be here primarily meant; but with a spiritual and eternal one; for without purification of the heart there is no salvation: this is the meetness for the undefiled inheritance; without the washing of regeneration, there is no seeing nor entering into the kingdom of God; and unless we are washed by Christ, and in his blood, we can have no part nor portion with him in the heavenly glory; none shall ascend the holy hill, or dwell in the holy place, but such who have clean hands, and a pure heart; without this there is no seeing of God, nor having communion with him; this is the way in which he saves men, Titus 3:5,

how long shall thy vain thoughts lodge within thee? or, "wilt thou suffer them to lodge within thee?" (z) if the question is of right, the answer is, they ought not to lodge one night, one hour, one moment; but if it is of fact, the answer is, they will have a place in the heart as long as we are in this tabernacle; but the words are spoken by way of complaint and reproof: the thoughts of men's hearts are vain, are taken up about vain and foolish things; and these not only pass to and fro, but have a lodging in the heart; and particularly vain are the thoughts of those who think themselves pure, and that their hearts are good, and trust in them; or that they can wash themselves from their wickedness; and that an outward reformation of life and manners is sufficient; and who think they can be saved without the washing of regeneration, and the blood of Christ. The Targum is,

"cleanse thine heart from doing evil, O Jerusalem, that ye may be saved; how long shall they endure and be stable who do violence, which is in the midst of thee?''

(z) "quousque morari sines", Pagninus, Montanus.