Now after the death of Jehoiada the princes of Judah came and paid homage to the king. Then the king listened to them.And they abandoned the house of the Lord, the God of their fathers, and served the Asherim and the idols. And wrath came upon Judah and Jerusalem for this guilt of theirs. Yet he sent prophets among them to bring them back to the Lord. These testified against them, but they would not pay attention. (2Ch 24:17-19)
It's always tragic when you read the account of a good king who turns bad. Joash after doing such great work in restoring the house of the Lord falls under bad influence when his good influence, Jehoiada the priest, is gone.
Yet here we read of the mercy and forbearance of God. He did not act in wrath straight away, but sent prophets among them, with the purpose of bringing them back to the Lord.
This is a simple phrase, but it communicates a lot about the purpose and nature of the prophetic gift. The prophets were not sent to write new scripture, as some suppose is the inevitable outcome of prophetic utterance. Nor were they sent to make bizarre and fanciful predictions about the future. They were raised up, from among the people themselves, to turn the hearts of the people to the Lord.
This is the true nature, not just of prophecy, but of all the gifts that the Holy Spirit distributes to his people. They operate among the people and they point them to the Lord.