The prophets and their prophetic office is directly connected to the covenant of grace that God made with his people, with Israel. One scholar calls them, "God's covenant prosecutors." They are like lawyers, attorneys whom God contracts with to represent his covenantal interest with his people, Israel. So, they are prosecuting attorneys. That's why they're so polemical and sometimes even accusatory. They are bringing a case against Israel. Some of them will even use that language — God has an argument, or a case, against Israel. They will assemble, in their imagery, the people before some divine court where a judge is listening to what they say and the people's defense to make a rendering of innocent or guilty. And this has been a history of them throughout the Old Testament. If you talk about Moses, he was the first great prophet. One scholar calls him the "pool" or the source out of which all the other prophets flow. Samuel would be the rapids of that stream, and all of the preaching prophets like Nathan and Gad who came out of that. And then there's this great school of writing or classical prophets with Isaiah and Ezekiel and Jeremiah and Daniel, and finally, culminating in this last great prophet who was the forerunner of Christ, John the Baptist. They are all covenant prosecutors. They are bringing repeatedly before Israel their covenant-breaking. The book they refer to the most in their prophecies is the book of Deuteronomy. That's their covenant treaty, that covenant agreement, that's the thing they keep pointing back to and calling Israel and the New Testament church to be faithful to. So they, perhaps more than maybe any other writers or speakers in the Bible, really understand not just what the covenant is but how it relates to God's church, God's people, and how we live as the people of the covenant of grace.