Jeremiah

Who

Jeremiah, with his scribe Baruch, who is named as writing it down.

When

From about 627 BC to after the fall of Jerusalem in 586.

What it is

Forty years of warning nobody wanted, from a man who did not want to give it, watching it come true.

What to watch for

It is not in chronological order. He is also the most personally miserable writer in the Bible, and says so.

For I know the plans I have for you, declares the LORD, plans to prosper you and not to harm you, to give you a future and a hope.Jeremiah 29:11