Isaiah 5:30
And in that day they shall roar against them like the roaring of the sea: and if one look unto the land, behold darkness and sorrow, and the light is darkened in the heavens thereof. And in that day they shall roar against them like the roaring of the sea: and if one look unto the land, behold darkness and sorrow, and the light is darkened in the heavens thereof.
Isaiah 5:30 stands in Isaiah 2-5, where chapter 5 portrays Israel and Judah as an unfruitful vineyard under woes pronounced on those who depart from God. The forceful depiction there is of Judah's awful backsliding. The vineyard image means the Lord nourished His children as a well-kept vineyard, but they brought forth wild grapes and rebelled against Him.
The judgment for that rebellion was that the Lord would break down the wall of the vineyard, have it trodden down, and command the clouds to send no rain upon it. This proves the covenant was conditional, broken by disobedience, with the claim to the land forfeited. The warnings to Judah pointed to the sure consequences of following Israel's course.
The verse itself describes a day of judgment when attackers roar against the people like a raging sea, while the land below is dark with distress and sorrow and the light in the heavens over it is darkened. It stands among prophecies warning of coming social upheaval and distress, giving warning of perilous times and of the consequences of oppression. The turning away of God's people described here is a type of last-day apostasy, so the warnings in Isaiah's prophecies remain relevant to the last days. Work for the Lord's vineyard should remind vineyard keepers of their duty toward God's vineyard, and the teaching of Jesus through a vineyard parable should renew their diligence.