Bonhoeffer’s approach to the Psalter is rare. It was rare in his day and it is rare in ours. May Jesus help us by His gracious Spirit and teach us how to pray in His Name, as Bonhoeffer pursued. The below is an excerpt from his small and rich book on the Psalms. My it be an appetizer for the rest of the book that you can get here: Psalms: The Prayer Book of the Bible
From Learning to Pray in the Name of Jesus
The Holy Scripture is the Word of God to us. But prayers are the words of men. How do prayers then get into the Bible? Let us make no mistake about it, the Bible is the Word of God even in the Psalms. Then are these prayers to God also God’s own word? That seems rather difficult to understand. We grasp it only when we remember that we can learn true prayer only from Jesus Christ, from the word of the Son of God, who lives with us men, to God the Father, who lives in eternity.
Jesus Christ has brought every need, every joy, every gratitude, every hope of men before God. In his mouth the word of man becomes the Word of God, and if we pray his prayer with him, the Word of God becomes once again the word of man. All prayers of the Bible are such prayers which we pray together with Jesus Christ, in which he accompanies us, and through which he brings us into the presence of God. Otherwise there are no true prayers, for only in and with Jesus Christ can we truly pray.
If we were dependent entirely on ourselves, we would probably pray only the fourth petition of the Lord’s Prayer. But God wants it otherwise. The richness of the Word of God ought to determine our prayer, not the poverty of our heart.
If we want to read and to pray the prayers of the Bible and especially the Psalms, therefore, we must not ask first what they have to do with us, but what they have to do with Jesus Christ. We must ask how we can understand the Psalms as God’s Word, and then we shall be able to pray them. It does not depend, therefore, on whether the Psalms express adequately that which we feel at a given moment in our heart. If we are to pray aright, perhaps it is quite necessary that we pray contrary to our own heart. Not what we want to pray is important, but what God wants us to pray. If we were dependent entirely on ourselves, we would probably pray only the fourth petition of the Lord’s Prayer. But God wants it otherwise. The richness of the Word of God ought to determine our prayer, not the poverty of our heart. 
- Bonhoeffer, Dietrich, and Eberhard Bethge. Psalms: The Prayer Book of the Bible. Minneapolis: Augsburg Pub. House, 1970. ↩