What does Psalm 91:16 mean?

The Lord promises long life to the person who trusts Him and loves Him. Other references in Scripture make it clear this is not a simplistic, absolute promise of invincibility (Psalm 3:1–2). Jesus, in fact, refuted a twisting of this very psalm when Satan tried to make that mistaken claim (Matthew 4:4–7; Psalm 91:11–12). It's true, however, that those who follow godly wisdom are much less likely to suffer unnecessary harm (Proverbs 1:7; 9:11–12). That comes with avoiding unhealthy habits, dangerous lifestyles, unneeded strife, and so forth (1 Corinthians 6:19–20; Galatians 5:16–26). Of course, a believer may die young, but his death is simply a change of address from earth to heaven. He passes from temporal life to eternal life. The Lord also promises salvation. for the Christian, this can sometimes mean deliverance in this life, but it always means the forgiveness of sins and the gift of eternal life (John 3:16–18).

Longevity was prized by the people of Israel. God had promised them in Exodus 20:12 that their days would be long in the Promised Land if they honored father and mother. Genesis 25:8 reports that Abraham, the friend of God (James 2:23), "died in a good old age, an old man and full of years." The Lord gives not only quantity of days but also quality of life. He satisfies the trusting believer with long life!