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 2

2:11 And I raised up of your sons for prophets, and of your young men for Nazarites. Is it not even thus, O ye children of Israel? saith the LORD.