Charles H. Spurgeon on Psalms 18:47

"It is God that avengeth me, and subdueth the people under me." To rejoice in personal revenge is unhallowed and evil, but David viewed himself as the instrument of vengeance upon the enemies of God and his people, and had he not rejoiced in the success accorded to him he would have been worthy of censure. That sinners perish is in itself a painful consideration, but that the Lord's law is avenged upon those who break it is to the devout mind a theme for thankfulness. We must, however, always remember that vengeance is never ours, vengeance belongeth unto the Lord, and he is so just and withal so longsuffering in the exercise of it, that we may safely leave its administration in his hands.