The prophet here turns his speech, in God’s name, to the men of the place where he lived. We have heard what words he proclaimed towards the north (Jer. 3:12), for the comfort of those that were now in captivity and were humbled under the hand of God; let us now see what he says to the men of Judah and Jerusalem, who were now in prosperity, for their conviction and awakening. In these two verses he exhorts them to repentance and reformation, as the only way left them to prevent the desolating judgments that were ready to break in upon them. Observe,

I. The duties required of them, which they are concerned to do.

1. They must do by their hearts as they do by their ground that they expect any good of; they must plough it up (Jer. 4:3): “Break up your fallow-ground. Plough to yourselves a ploughing (or plough up your plough land), that you sow not among thorns, that you may not labour in vain, for your own safety and welfare, as those do that sow good seed among thorns and as you have been doing a great while. Put yourselves into a frame fit to receive mercy from God, and put away all that which keeps it from you, and then you may expect to receive mercy and to prosper in your endeavours to help yourselves.” Note, (1.) An unconvinced unhumbled heart is like fallow-ground, ground untilled, unoccupied. It is ground capable of improvement; it is our ground, let out to us, and we must be accountable for it; but it is fallow; it is unfenced and lies common; it is unfruitful and of no advantage to the owner, and (which is principally intended) it is overgrown with thorns and weeds, which are the natural product of the corrupt heart; and, if it be not renewed with grace, rain and sunshine are lost upon it, Heb. 6:7, 8. (2.) We are concerned to get this fallow-ground ploughed up. We must search into our own hearts, let the word of God divide (as the plough does) between the joints and the marrow, Heb. 4:12. We must rend our hearts, Joel 2:13. We must pluck up by the roots those corruptions which, as thorns, choke both our endeavours and our expectations, Hos. 10:12.

2. They must do that to their souls which was done to their bodies when they were taken into covenant with God (Jer. 4:4): “Circumcise yourselves to the Lord, and take away the foreskin of your heart. Mortify the flesh and the lusts of it. Pare off that superfluity of naughtiness which hinders your receiving with meekness the engrafted word, Jas. 1:21. Boast not of, and rest not in, the circumcision of the body, for that is but a sign, and will not serve without the thing signified. It is a dedicating sign. Do that in sincerity which was done in profession by your circumcision; devote and consecrate yourselves unto the Lord, to be to him a peculiar people. Circumcision is an obligation to keep the law; lay yourselves afresh under that obligation. It is a seal of the righteousness of faith; lay hold then of that righteousness, and so circumcise yourselves to the Lord.”

II. The danger they are threatened with, which they are concerned to avoid. Repent and reform, lest my fury come forth like fire, which it is now ready to do, as that fire which came forth from the Lord and consumed the sacrifices, and which was always kept burning upon the altar and none might quench it; such is God’s wrath against impenitent sinners, because of the evil of their doings. Note, 1. That which is to be dreaded by us more than any thing else is the wrath of God; for that is the spring and bitterness of all present miseries and will be the quintessence and perfection of everlasting misery. 2. It is the evil of our doings that kindles the fire of God’s wrath against us. 3. The consideration of the imminent danger we are in of falling and perishing under this wrath should awaken us with all possible care to sanctify ourselves to God’s glory and to see to it that we be sanctified by his grace.