Charles H. Spurgeon on Psalms 109:30

I will greatly praise the Lord with my mouth. In the celebration of God's praises, there can be no question that these must issue from the heart ere they can be uttered by the lips; at the same time, it would be an indication of great coldness, and of want of fervour, did not the tongue unite with the heart in this exercise. The reason why David makes mention of the tongue only is, that he takes it for granted that, unless there be a pouring out of the heart before God, those praises which reach no farther than the ear are vain and frivolous; and, therefore, from the very bottom of his soul, he pours forth his heart felt gratitude in fervent strains of praise; and this he does from the same motives which ought to influence all the faithful —the desire of mutual edification; for to act otherwise would be to rob God of the honour which belongs to him. —John Calvin.