The First Part.
1....“Hear ye these things, all you nations”. Not then you only who are here. For of what power is our voice so to cry out, as that all nations may hear? For Our Lord Jesus Christ has proclaimed it through the Apostles, has proclaimed it in so many tongues that He sent; and we see this Psalm, which before was only repeated in one nation, in the Synagogue of the Jews, now repeated throughout the whole world, throughout all Churches; and that fulfilled which is here spoken of, “Hear ye these words, all you nations.”...Of whom you are: “With ears ponder, all you that dwell in the world.” This He seems to have repeated a second time, lest to have said “hear,” before, were too little. What I say, he says, “hear, with ears ponder,” that is, hear not cursorily. What is, “with ears ponder”? It is what the Lord said, “he that has ears to hear, let him hear:” for as all who were in His presence must have had ears, what ears did He require save those of the heart, when He said, “he that has ears to hear, let him hear”? The same ears also this Psalm does smite. “With ears ponder, all you that dwell in the world.” Perhaps there is here some distinction. We ought not indeed to narrow our view, but there is no harm in explaining even this view of the sense. Perhaps there is some difference between the saying, “all nations,” and the saying, “all you that dwell in the world.” For perchance he would have us understand the expression, “dwell in,” with a further meaning, so as to take all nations for all the wicked, but the dwellers of the world all the just. For he does inhabit who is not held fast: but he that is occupied is inhabited, and does not inhabit. Just as he does possess whatever he has, who is master of his property: but a master is one who is not held in the meshes of covetousness: while he that is held fast by covetousness is the possessed, and not the possessor....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)