We know that Zephaniah prophesied at the same time as Jeremiah, and after 623 (when the book of the Law was discovered in the Temple) because Zephaniah quotes from this book of the Law, or Deuteronomy, four times (1:13, 15, 17; 2:2).

“Search” refers to a diligent, detailed search that involves looking in every corner and sifting
through things. Zephaniah is predicting the Babylonian siege of Jerusalem in 586 BC, but
Josephus records a similar thorough “searching” through the underground sewers of Jerusalem
by the Romans in 70 AD in order to kill or capture every Jew.

“Dregs” or “lees” are the refuse or deposits of dead yeast, residual yeast from the fermentation
of wine, or the remnants with the sediment that must be removed to preserve the desirable flavor of the wine.

Zephaniah uses the image of wine that becomes harsh when it is not removed from the dregs.
Wine is supposed to be processed by pouring it back and forth to separate the wine from the
dregs. If this doesn't happen, a crusty layer forms on the wine while it ferments too long and the wine's flavor becomes bitter and harsh. The wine must be removed from the dregs so that its
flavor is not ruined.

The men of Judah had become complacent since they had not separated themselves from the evil
or the corruption of their culture. So, the bitter, harsh flavor of worldliness had ruined the flavor of
their lives. The image of “wine left on its dregs” represents the complacent attitude toward God
and a calloused heart towards God’s Spirit.

One of the areas in which their complacency had allowed them to error was their judgment of God’s activity in their communities. They assumed that since they were not instantly punished when
they lived in sin and rebellion (or, stayed mixed with the dregs) that the Lord was not going to
do anything. Since they were complacent, they figured God would also be complacent. But, God promises he will be taking swift action against them.

Jeremiah uses the image of wine left with its dregs in Jeremiah 48:11,

“Moab has been at rest from youth, like wine left on its dregs, not poured from one jar to another – she has not gone into exile. So she tastes as she did and here aroma is unchanged. But days are coming, when I will send me who pour from jars, and they will pour her out; they will empty her jars and smash her jugs.”