9 We see therefore these things in that work of His; we praise, we marvel at, we bless God; let us see what He has done among men for His people. “Who smote the first-born of Egypt”. But withal those divine doings are told which you might love, those are not told which you might fear. Attend, and see that also when He is angry, He does what He wills. “From man even unto beast. He sent signs and wonders into the midst of you, O Egypt!”. You know, you have read what the hand of the Lord did by Moses in Egypt, to crush and cast down the proud Egyptians, “on Pharaoh and on all his servants.”
Little did He in Egypt: what did He after His people was led out thence? “Who smote many nations”, who possessed that land, which God willed to give His people. “And slew mighty kings, Sehon king of the Amorites, and Og the king of Bashan, and all the kingdoms of Canaan”. All these things which the Psalm records simply, do we read likewise in others of the Lord's books, and there the hand of the Lord is great. When you see what has been done to the wicked, take heed lest it be done to you....But when the good man sees what the wicked has suffered, let him cleanse himself from all iniquity, lest he fall into a like punishment, a like chastisement.
Then you have thoroughly understood these things. What did God then? He drove out the wicked, “And he gave their land for an inheritance, even an inheritance to Israel His servant”.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)