In Does God Hear Us?
Eberhard Arnold writes,
I have heard people say, “At one time I was very near to God, but he didn’t hear me. Since then I haven’t been so sure about him.” Such people fail to recognize that God wanted to say something to them, namely, that none of us really knows what to pray for. We certainly do not always know what is best. If we want to give God orders according to our will, if we want to dictate God's direction through our prayers, then such prayers are not under the blessing of God. Rather, these prayers are born of the spirit of darkness, the spirit that told Eve, "You shall be like God."
True prayer acknowledges that of ourselves we are incapable of striking the right course in prayer. True prayer demands complete surrender and complete confidence, so that we can say, "We do not know what we ought to pray for, but the Spirit himself intercedes for us with groans that words cannot express" (Romans 8:26-30).
When we come before God, we do not always find the right words. We are often unclear about what we want to pray for. We are sometimes so weak we cannot even gather our thoughts sufficiently to frame our prayer in words at all. Yet there is one who knows everything that is in our hearts. If we know him, then we will say with Peter, "Lord, you know all things. You know that I love you" (John 21:15-17).