There is no occasion to separate Jeremiah 4:3, Jeremiah 4:4, from the preceding prophecy. We have other instances of as sudden a transition from the Israelites (in the narrower sense) to the men of Judah (see Isaiah 8:6-14; Isaiah 10:1-4; Isaiah 28:1-6; in the writer's commentary).
For thus, etc. "For" is here not causal, but explanatory: "I say this not only to the men of Israel, but to you, O men of Judah, who need the admonition to repentance, how deeply!" (see Jeremiah 5:2).
Break up your fallow ground; the same figure as in Hosea 10:12. To understand it we must read the clause in connection with the following one. Sow not among thorns. The prophet means, though he does not say so, the roots which will spring up into thorns.
"Do not plant your good resolutions in a heart filled up with the roots of thorns, but first rake up the soil, and clear it of noxious germs, and then sow the seed which will grow up in a holy life" (comp.