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 3

3:8 The lion hath roared, who will not fear? the Lord GOD hath spoken, who can but prophesy?