Charles H. Spurgeon on Psalms 149:6

Let the high praises of God be in their mouth and a two edged sword in their hand. Praise and power go ever hand in hand. The two things act and react upon each other. An era of spiritual force in the Church is always one of praise; and when there comes some grand outburst of sacred song, we may expect that the people of God are entering upon some new crusade for Christ. Cromwell's Ironsides were sneeringly called Psalm singers; but God's Psalm singers are always Ironsides. He who has a "new song in his mouth" is ever stronger, both to suffer and to labour, than the man who has a dumb spirit and a hymnless heart. When he sings at his work, he will both do more and do it better than he would without his song. Hence, we need not be surprised that all through its history the Church of God has travelled "along the line of music." —William Taylor, in "The Study," 1873.