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 1

1:8 And I will cut off the inhabitant from Ashdod, and him that holdeth the sceptre from Ashkelon, and I will turn mine hand against Ekron: and the remnant of the Philistines shall perish, saith the Lord GOD.