4:3 fallow ground. Fallow ground is ground that has been plowed and readied for sowing, but then is withheld and allowed to remain unproductive and useless. Note also Hosea 10:12.

4:6 evil from the north. The king of Babylon, approaching from the north, was “on his way” (Jeremiah 4:7), and would eventually “make thy land desolate.” He is called “a lion,” “the destroyer of the Gentiles,” “a dry wind” (Jeremiah 4:11), and “a whirlwind” (Jeremiah 4:13).

4:23 the earth. The word translated “earth” (Hebrew eretz) is commonly translated “land,” depending upon context. It is translated “land” in Jeremiah 4:5, for example (as well as in Jeremiah 4:7,20,27), obviously referring to the land of Judah. It should be translated “land” in this verse also, in consistency with the whole context of the chapter.

4:23 without form, and void. Because this phrase, “without form and void,” is applied to the primeval earth in Genesis 1:2, many who advocate the “gap theory,” hoping to accommodate the long evolutionary ages in Genesis between the first two verses of the Bible, have used this verse as a “proof text” for a hypothetical pre-Edenic cataclysm which destroyed the original creation of Genesis 1:1. The gap theory, however, is indefensible both geologically and theologically (see notes on Genesis 1:2). The context here, both before and after (Jeremiah 4:16,31), make it clear that the whole chapter is describing the coming destruction of Judah, not some mysterious prehistoric cataclysm destroying the primeval world.

4:24 the mountains, and, lo, they trembled. The coming waves of invasion and destruction by the armies of Babylon would also be punctuated with earthquakes and storms (Jeremiah 4:28), finally leaving the land desolate.