If our need is to number our days by contrasting their shortness with the eternal nature of God, then our prayer to God is that He would teach us: “Teach us to number our days.” We will never learn that lesson in our own strength.
Teach us to number our days that we may get a heart of wisdom (Psalm 90: 12).
This verse is often treated as if it were a proverb that means, “Life is short, so live wisely.” But in the context of the whole psalm, it means much more than that, as we will see. It is a key part of a meditation on God and on living as the people of God.
In Hebrew, verse 12 begins with the words “to number our days.” This phrase picks up the theme of time that is so pervasive in this psalm. A reflection on time leads us to see how weak we are and how short our lives are: “You return man to dust and say, ‘Return, O children of man!’ … You sweep them away as with a flood; they are like a dream, like grass that is renewed in the morning: in the morning it flourishes and is renewed; in the evening it fades and withers… The years of our life are seventy, or even by reason of strength eighty; yet their span is but toil and trouble; they are soon gone, and we fly away” (vv. 3, 5–6, 10). Here, Psalm 90 shows its connection to the concerns of Psalm 89 about man’s frailty: “Remember how short my time is! For what vanity you have created all the children of man! What man can live and never see death? Who can deliver his soul from the power of Sheol?” (Ps. 89:47–48). Such realism about our weakness is the necessary foundation of any true wisdom. “O Lord, make me know my end and what is the measure of my days; let me know how fleeting I am” (Ps. 39:4).
The shortness and weakness of human life are the fruit of sin and judgment in the world. The psalmist acknowledges that sin frankly, saying, “You have set our iniquities before you, our secret sins in the light of your presence” (Ps. 90:8). He knows that his holy God visits His judgment on sinners. “For all our days pass away under your wrath; we bring our years to an end like a sigh… . Who considers the power of your anger, and your wrath according to the fear of you?” (vv. 9, 11). It is surely frightening to think that God’s wrath will equal all the obedience that is due to Him.