Psalm 40 tells of a man who was stuck in a slimy pit, bogged down in mud and mire, but then was rescued by God, who set his feet on a rock and gave him a firm place to stand. That man was King David.
The New Testament perspective on the idea of an alien is found in several places, for example, in 1 Peter 2:11: "Dear friends, I urge you, as aliens and strangers in the world, to abstain from sinful desires, which war against your soul." It is an appeal to live like citizens of the heavenly country to which we belong and to which we are going and not as citizens of this earth.
When we do come to understand our own weakness and creatureliness in the context of our suffering, we tend to ask these kinds of questions: “What does God want with me?" “Why does he care what I do? Nothing I do can possibly affect him or hurt him. I don’t have anything to contribute to him.” “Why doesn't God just forget about me and leave me alone."
This is the meaning of verse 4. Verse 4 does not mean: "I am weary of this suffering; tell me when I am going to die so this will end" or "Life is too short for all I have been given to do; this is unfair." Instead, it means, as J. J. Stewart Perowne expressed it, "Make me rightly to know and estimate the shortness and uncertainty of human life, that so, instead of suffering myself to be perplexed with all that I see around me, I may cast myself the more entirely upon thee."3 This is exactly what David does in the verse immediately following this stanza, that is, in verse 7.
We should learn a number of things from David's conduct: 1) What we say is vitally important; we can sin with our mouths as well as with our other bodily members; 2) It is better to be silent than to say things that can be used against God by wicked persons; 3) We should not be anxious to share such grief even with godly persons; and 4) We should bring our troubles to God.
