John Calvin in Commentary on Psalms commenting on Psalm 51:8:
It is the word of God alone which can first and effectually cheer the heart of any sinner. There is no true or solid peace to be enjoyed in the world except in the way of reposing upon the promises of God. Those who do not resort to them may succeed for a time in hushing or evading the terrors of conscience, but they must ever be strangers to true inward comfort.
And, granting that they may attain to the peace of insensibility, this is not a state which could satisfy any man who has seriously felt the fear of the Lord. The joy which he desires is that which flows from hearing the word of God, in which he promises to pardon our guilt, and readmit us into his favor. It is this alone which supports the believer amidst all the fears, dangers, and distresses of his earthly pilgrimage; for the joy of the Spirit is inseparable from faith.