Thus says Yahweh: "For three transgressions of Damascus, yes, for four, I will not turn away its punishment; Because they have threshed Gilead with threshing instruments of iron;
Damascus was the capital city of Aram (Syria), and it stands for the whole nation by metonymy. Similarly the capitals Jerusalem and Samaria often represent their respective nations, Judah and Israel, by metonymy, in biblical literature. Yahweh promised that He would not turn back the punishment due Aram because the Arameans had proved to be a scourge to the people of Israel. Threshing Gilead, a transjordanian part of Israel, with sharp iron implements pictures the plowing up of that part of the nation militarily (cf. Isaiah 41:15; Micah 4:13; Habakkuk 3:12). [Note: See D. A. Hubbard, Joel and Amos, p. 131.] Israelite citizens and territory had suffered greatly during constant battles with the Arameans, especially in Transjordan (cf. 2 Kings 8:7-12; 2 Kings 10:32-33; 2 Kings 13:3-7). The Aramean rulers Hazael and his son Ben-hadad III had repeatedly invaded and conquered Israel between 842 and 802 B.C.