The middle of the superscription of Psalm 39, which may be part of a postscript to the previous psalm, says "To Jeduthun," referring to "one of David's three choir leaders (1 Chronicles 16:41-41, 1 Chronicles 25:1, 1 Chronicles 25:6, 2 Chronicles 5:12; called his 'seer' in 2 Chronicles 35:15). Jeduthun is probably also Ethan of 1 Chronicles 6:44 [and] 1 Chronicles 15:19; if so, he represented the family of Merari, even as Asaph did the family of Gershon and Heman the family of Kohath, the three sons of Levi (see 1 Chronicles 6:16, 33, 39, 43-44)" (Zondervan NIV Study Bible, note on Psalm 39 title). The end of the superscription, "A Psalm of David," no doubt goes with Psalm 39.

In this prayer David is "deeply troubled by the fragility of human life. He is reminded of this by the present illness through which God is rebuking him (vv. 10-11) for his 'transgression' (v. 8)" (note on Psalm 39).

As the psalm opens, we see that David has made a determination to not speak aloud, presumably of his anguish, lest this make its way to his or God's enemies. The Expositor's Bible Commentary notes on verse 2 that he "fears that he may be misunderstood or that he may speak irreverently and give occasion to the enemy. For the sake of God, he vowed to be silent in his suffering." Yet verses 8-9 make it appear that David did not want to admit to detractors that his sickness was a result of God punishing him for sin. So the sin he was now guarding against could have been that of defending his reputation against criticism that might have been just (if not coming from hypocrites). Whatever the reasoning, it may help to explain his silence in the previous psalm, especially if it concerns the same illness (see Psalm 38:13-14).

At last, David says that he had to vent his anguish and frustration (verse 3). But it seems that he does the venting to God (verse 4). He begins by basically asking, "Okay, when am I going to die? How much time do I have left?" (as it seemed this could be the end)—and complaining that human life is fleeting, like the few inches of a handbreadth in length and a wisp of vapor in substance (verses 4-6, 11). All that people did seemed so pointless (verse 6). This is the theme running through the book of Ecclesiastes.

Still, David hopes in and prays for God's healing (verses 7, 10, 12-13). He notes that he has lived not as one tied to this world but as a "stranger" or "alien" (a foreigner to this evil world) and a "sojourner" (a traveler or passing guest). And this has not been on his own but rather, as he says to God, "with You" (verse 12). The book of Hebrews says that God's saints "all died in faith, not having received the promises, but having seen them afar off were assured of them, embraced them and confessed that they were strangers and pilgrims on the earth. For those who say such things declare plainly that they seek a homeland...a better, that is, a heavenly country" (Hebrew 11:13-16; compare 1 Peter 2:11-12). So in saying what he did, David was not only reminding God of his relationship with Him, but he was also expressing his hope in God's Kingdom. If it was time for him to die, he trusted in His future with God.

Yet David is not resigned to death. He still prays that God will remove His gaze so that he may regain strength and not die (Psalm 39:13). This does not mean, as some commentators suggest, that David is praying for God to leave him alone. For on his own David could never recover. Rather, we should understand the terminology in light of Psalm 80:16, which says that God's people perish at the rebuke of His countenance. The idea is that when He gazes on them in anger, they wither and are consumed. So Psalm 80 repeatedly asks that God would cause His face to shine—to smile favorably. David is likewise pleading for God to turn away His angry gaze of judgment—and, as stated in verse 7, he is hopeful that God will.