Introduction to Psalms

David was the penman of most of the psalms, but some evidently were composed by other writers, and the writers of some are doubtful. But all were written by the inspiration of the Holy Ghost; and no part of the Old Testament is more frequently quoted or referred to in the New. Every psalm either points directly to Christ, in his person, his character, and offices; or may lead the believer's thoughts to Him. And the psalms are the language of the believer's heart, whether mourning for sin, thirsting after God, or rejoicing in Him. Whether burdened with affliction, struggling with temptation, or triumphing in the hope or enjoyment of deliverance; whether admiring the Divine perfections, thanking God for his mercies, mediating on his truths, or delighting in his service; they form a Divinely appointed standard of experience, by which we may judge ourselves. Their value, in this view, is very great, and the use of them will increase with the growth of the power of true religion in the heart. By the psalmist's expressions, the Spirit helps us to pray. If we make the psalms familiar to us, whatever we have to ask at the throne of grace, by way of confession, petition, or thanksgiving, we may be assisted from thence. Whatever devout affection is working in us, holy desire or hope, sorrow or joy, we may here find words to clothe it; sound speech which cannot be condemned. In the language of this Divine book, the prayers and praises of the church have been offered up to the throne of grace from age to age.

-- taken from Matthew Henry's Concise Commentary