Midrash sa Amos 1:3: Sifrei Devarim

Similarly, (Amos 3:1) "Hear this prophecy which the L-rd spoke, etc." Now did Amos prophesy only these? Is it not written (Amos 1:1) "The words of Amos, one of the herders of Tekoa, who saw visions concerning Israel"? The intent (of "this prophecy") is that they were words of rebuke, viz. (Ibid. 4;1) "Hear this thing, you cows of Bashan on Mount Shomron, etc." The "cows of Bashan" are their (corrupt) judges.

(Devarim, Ibid.) "lest their oppressors estrange them": When Israel is in distress, the nations estrange them, as if they did not exist in the world. And thus we find that when Israel wanted to flee to the north they handed them over (to their foes), viz. (Amos 1:9) "Thus said the L-rd: For three transgressions of Tyre, etc." When they wanted to flee to the south, they handed them over, viz. (Ibid. 6) "Thus said the L-rd: For three transgressions of Azza, etc." When they wanted to flee to the east, they handed them over, viz. "Thus said the L-rd: For the three transgressions of Damascus, etc." When they wanted to flee to the west, they handed them over, viz. (Isaiah 21:13) "The prophecy for Arav: In the forest, in Arav shall you lodge, O caravans of the Dedanites, etc."