Adam Clarke on Psalms 83:4

Let us cut them off - Let us exterminate the whole race, that there may not be a record of them on the face of the earth. And their scheme was well laid: eight or ten different nations united themselves in a firm bond to do this; and they had kept their purpose so secret that the king of Judah does not appear to have heard of it till his territories were actually invaded, and the different bodies of this coalition had assembled at En-gedi. Never was Judah before in greater danger.