and my tongue rejoices
The rejoicing of the tongue signifies verbal expression of the inner joy felt by the heart. In the culture of ancient Israel, verbal praise and singing were integral to worship and community life. This phrase suggests that the psalmist's joy is so profound that it naturally overflows into spoken or sung praise. This rejoicing can be seen as a form of testimony to others about God's goodness and faithfulness.

my body also will dwell securely
This phrase conveys a sense of physical safety and well-being. In the historical context, security was a significant concern due to threats from enemies and instability. The psalmist's confidence in dwelling securely reflects trust in God's protection over all aspects of life, including physical safety. This assurance can also be seen as a foreshadowing of the resurrection, where believers find ultimate security in eternal life. The idea of dwelling securely connects to other scriptures that speak of God's protection, such as Psalm 23:4 and Psalm 91:1. Additionally, this phrase can be viewed as a type of Christ, who, through His resurrection, provides believers with the hope of eternal security.

The single word “Therefore” pulls everything David has just declared into one sweeping conclusion.

• Earlier in the psalm he said, “The LORD is my chosen portion” (Psalm 16:5) and “I have set the LORD always before me” (Psalm 16:8). Because God Himself is David’s unshakable security, he now draws a natural result.

• Peter quotes Psalm 16 in Acts 2:25-28 to show that Jesus trusted the Father perfectly, so the resurrection was certain. If Christ could rest on that promise, believers can rest on it as well (Romans 6:5).

• The word signals a settled confidence built on a previously stated reality, not on shifting emotion (Psalm 62:5-6).

Gladness begins deep within. David’s inner life responds first.

• Real joy is more than circumstances; it’s rooted in the presence of God (Psalm 21:6; John 15:11).

• This glad heart is possible because guilt is removed; David has taken refuge in the Lord (Psalm 16:1) much like Paul later rejoices in being justified by faith (Romans 5:1-2).

• Even in hardship, that inner gladness remains steady, echoing Habakkuk 3:17-18, where the prophet chooses to “rejoice in the LORD” despite loss.

What fills the heart spills out of the mouth.

• Praise moves from the private chamber of the heart to the public arena of speech (Psalm 71:8; Hebrews 13:15).

• Luke records that the resurrected Christ’s followers were “continually in the temple praising God” (Luke 24:53), living out the reality David foretold.

• Our speech becomes a testimony of trust, just as Paul and Silas sang hymns in prison (Acts 16:25). A rejoicing tongue shows the world where our hope lies (1 Peter 3:15).

Trust reaches all the way to physical existence.

• David looks beyond present safety to the assurance that even in death, his flesh is not abandoned (Psalm 16:10). That hope is fulfilled perfectly in Christ’s resurrection (Acts 13:35-37).

• For believers, the promise extends to bodily resurrection (1 Corinthians 15:20-23). Because Jesus lives, our bodies, too, will “sleep” in confident security, awaiting awakening glory (1 Thessalonians 4:14).

• Even before the final resurrection, the Lord grants nightly rest: “In peace I will lie down and sleep, for You alone, O LORD, make me dwell in safety” (Psalm 4:8). The same God who guards the soul guards the body.

Psalm 16:9 sketches a three-fold chain reaction of faith: confidence in God (“Therefore”) births inner gladness, which overflows into verbal praise, and finally settles into bodily security now and forever. What God secures inwardly He also secures outwardly, culminating in the resurrection proved in Christ and promised to every believer.

Shall rest in hope.--This follows the Vulg. The LXX. also have "shall tabernacle in hope." The true rendering, however, is shall rest in security. In "heart, soul, flesh," the poet comprises the whole living man. (Comp. 1Thessalonians 5:23.) The psalmist feels that the body must share with the soul the immunity from evil which is insured by fellowship with God. Carried out to its full issue, the logical conclusion of this is the doctrine of immortality; but we must not see a conscious reference to it here.