Psalm 39:4 says, “O Lord, make me know my end and what is the measure of my days; let me know how fleeting I am!” (ESV). In this verse, David pleads with God to help him understand the brevity of his life. The verses that follow also highlight the futile nature of human life in light of God’s eternal, timeless nature (see also Psalm 90:4).
God helps us to know the measure of our days by regularly reminding us of our temporary place in this world. In Job 7:7, we are told that our lives are “but a breath.” Psalm 102:3 says that our days “vanish like smoke.” And in the New Testament, James 4:14 says, “You are a mist that appears for a little while and then vanishes.” Because our lives don’t last long, much like breath, smoke, and mist, God wants to teach us how to measure our days so that we might acknowledge our forever need for Him. We would be nothing without God, who is eternal and all-powerful.
Another way God makes us know the number of our days is by reminding us of how our sinful actions lead to death. Romans 3:23 says that all have sinned and fall short of God’s glory. Romans 6:23 says that “the wages of sin is death.” But 2 Peter 3:9 teaches us that God doesn’t want anyone to perish. Instead, He wants all people to turn to Him in repentance and seek out His grace. By teaching us to know the measure of our days, then, God is showing us His desire for us to repent of our sins before our lives are over. In other words, God wants us to save us from the judgment of the second death while there is still time (see Revelation 20:14–15).
Knowing, therefore, that we’ve all sinned and will die at some point in the future, we should pray like David in Psalm 39:4 and ask God to show us the number or extent of our days—that is, that we would be reminded that our days are numbered. We should humbly place ourselves before God and acknowledge our need for His eternal grace.
Moses says this in Psalm 90:12 when he asks God to teach him to measure his days so that he may gain a heart of wisdom. The purpose of knowing the measure of our days is that we might live righteously toward God. Our lives will come to an end, and we should make the most of each day we’re given. We should strive to fulfill the two most important commandments in the Bible: loving God and loving others (Mark 12:29–31). Our lives on this earth are short, and we shouldn’t waste our limited time in selfish living and sin. Rather, we should use our time to honor God with our lives by living according to His Word.
Ecclesiastes 12:13–14 summarizes our responsibility:
”Here is the conclusion of the matter:
Fear God and keep his commandments,
for this is the duty of all mankind.
For God will bring every deed into judgment,
including every hidden thing,
whether it is good or evil.”
God makes us to know the measure of our days by showing us the finitude of our lives and by reminding us of how our sinful actions ultimately lead to death.