Ps 39 title Jeduthun (probably another name for Ethan) also appears in the titles of Pss 62 and 77. According to 1Ch 16:41, he was one of David’s chief musicians. If this is not a reference to Jeduthun himself, it may refer to his descendants or a group of musicians using his name (perhaps derived from his own musical style or school).
39:1-2 The reason for the psalmist’s silence was to keep from sinning by voicing his protest to God. The same idea occurs in 73:15, but in that text the protest is specifically identified as the belief that God is ignoring the prosperity of the wicked. In this psalm it could be a condition of suffering that caused these feelings to emerge.
39:4-6 This request for God to make the psalmist aware that his days were short-lived shows that he knew his inner feelings must be held in check. He already knew this, but he wished for the Lord to instruct him. Vapor (Hb hevel) is sometimes translated as “breath” (Jb 7:7). It denotes in its literal sense a small puff of air. Figuratively, it refers to a meaningless existence or futile activities (Ps 94:11; Ec 1:2). When used together with shadow, the word emphasizes the fleeting nature of life (see note at 144:4). The lesson to be learned involves seeing everything as God sees it—from his perspective, rather than from the human perspective. Human accomplishments, however great they seem, fade away with the steady march of history. For those who trust in God, life has a meaning and significance that is not tied to earthly achievements.
39:9 The psalmist was speechless because there was no point in complaining about what God was doing in his life.
39:10-11 The most severe suffering from the psalmist’s perspective was God’s torment, which was being used as a corrective measure to bring him to his senses and to help him learn the lesson in vv. 4-6. One way that God uses suffering in the lives of his people is to discipline them as his children in a loving and corrective way (Heb 12:5-11).
39:12 Alien and temporary resident are terms for those who were not native inhabitants in the promised land. The Israelites were to consider themselves as foreigners and “resident aliens” in the Lord’s land (see 119:19; Lv 25:23; 1Ch 29:15). The use of the words here seems to indicate that the lesson of Ps 39:4-6 about the insignificance and fleeting nature of this earthly life had been learned.