Amos is the book of the herdsman from Tekoa, a small town in Judah. He receives a direct call from God to prophesy against the unrighteousness of both Judah and Israel. Amos is the first prophet to proclaim that God is the ruler of the whole world.

Amos 4

4:5 And offer a sacrifice of thanksgiving with leaven, and proclaim and publish the free offerings: for this liketh you, O ye children of Israel, saith the Lord GOD.