The psalmist confesses his wrongs, convinced that they are the cause of his misfortune, which is seen as God’s just punishment. The folly he confesses is his disregard of God’s laws (see comments on “foolishness” in 38.5b). Good News Translation has reversed the two lines for greater ease of understanding. Thou knowest my folly is sometimes rendered idiomatically as “you know I have had a twisted heart” or “you know that my heart has led me on a bad path.”

In some languages it is not possible or at least not natural to say that one’s sins are not hidden from thee. In such cases it will be necessary to switch to an active expression. However, the sense is that God knows fully the sins of the writer, and therefore one may translate “You know full well all my sins, O God.”

Quoted with permission from Bratcher, Robert G. and Reyburn, William D. A Handbook on the Book of Psalms. (UBS Helps for Translators). New York: UBS, 1991. For this and other handbooks for translators see here .