So teach us to number our days, that we may apply our hearts unto wisdom.
It is a wonderful thought that God has already lived all of our tomorrows. God has no yesterdays and no tomorrows. The Scriptures say, “Jesus Christ the same yesterday, and to day, and for ever” (Hebrews 13:8), but it’s not His yesterday—it’s yours and mine. Jesus Christ the Lord is the One who came out of Bethlehem, out of Judea, whose goings forth have been even from everlasting. He can’t have yesterdays and tomorrows, because yesterday is time and tomorrow is time, but God surrounds it all and God has already lived tomorrow. The great God who was present at the beginning when He said, “Let there be” and there was, is also now present at the end, when the worlds are on fire and all creation has dissolved and gone back into chaos—and only God and His redeemed saints remain. Remember that God has already lived our tomorrows….
The Scripture says in Psalm 90:12 that because God is eternal, we must learn “to number our days, that we may apply our hearts unto wisdom.” God is in our today because God was in our yesterday and will be in our tomorrow…. God is! And because God is, then God is here and God is now. God dwells in an everlasting and eternal now. AOGII059-060
Lord, You are eternal, but I am of now. Teach me to number my time-oriented days, so I might use them wisely. Amen. 
Proper Response to God’s Wrath (90:11–12)
11–12 The two previous motifs of “wrath” and “days” lead into a prayer for wisdom as the only legitimate and wise response to the human condition. People generally do not pay attention to the divine law of sin and retribution. One reason is that the full brunt of God’s anger is withheld and unknown to people. The frustrations in life are explained away or accepted as long as there are not too many problems. The greatness of God’s wrath should evoke fear, and that fear should be commensurate with God’s wrath (v. 11). Thus the psalmist calls for a wise response to the previous teaching on the nature of God in contradistinction to the nature of humans. His question “Who knows the power of your anger?” is to be understood as a strong affirmation: “Nobody knows the power of your anger!”
Though no one knows how God’s full anger will affect human existence, those who fear the Lord are more aware of the fierceness of his anger. The wise pray for “a heart of wisdom” (v. 12). Since no one “knows” (yôdēaʿ GK 3359, v. 11) how great God’s rage may be, the wise are receptive to divine revelation/instruction: “teach us” (hôdaʿ GK 3359, v. 12). The prayer consists of two parts. First, the wise ask to apprehend the brevity of life. The numbering of “days” (v. 12) is an act of recognition of the vast difference between God and finite human beings. Though life may have many pleasant surprises, God’s anger may come at any time; and the wise reckon continually with God’s existence and humankind’s accountability. Second, the wise apply themselves to obtaining a “heart of wisdom” (cf. Dt 5:29; 32:29). Brueggemann (Message of the Psalms, 113) observes that this heart “attends to the persistent reality of Yahweh’s Lordship.” Wisdom begins and ends with the Lord, as the wise seek the Lord in all of their ways (cf. Pr 1:7), and true wisdom begins with the petition for revelation and illumination: “Teach us.”
90:11, 12 The man of God stands in awe of the power of God that has been awakened in anger. Who, he wonders, can reverence Him adequately when one considers the immensity of His wrath? This much is sure: it should make us value every day of our lives and spend each one in obedience to Him, and in such a way that it will count for eternity.
90:11 Your fury … fear … due You? Instead of explaining away life’s curses, a wise person will recognize God’s wrath toward sin as the ultimate cause of all afflictions and consequently learn to fear God.
90:12 number our days. Evaluate the use of time in light of the brevity of life. heart of wisdom. Wisdom repudiates autonomy and focuses on the Lord’s sovereignty and revelation.
90:12 teach us to number our days. In view of the theme of the psalm, this refers especially to the ability to make the most of one’s days, since they are so few. The heart of wisdom would enable the faithful to live by the right priorities (cf. the “fear” of God, v. 11).
90:11 the fear due Fearing God means placing all other potential objects of fear or reverence in perspective and revering Him above else. Fearing God can be described as giving Him respect or honor. Verse 12 advocates a response to God’s power and wrath.
The fear of God is a pervasive concept throughout the Bible (Prov 1:7; 8:13; 9:10; compare Psa 111:10), including the Prophets (Isa 11:2; Jer 5:24), and the Psalms (Ps 2:11; 5:7; 15:4; 19:9; 33:8).
90:12 teach us to number our days A response to God’s power and wrath—emphasizing that people should pay attention to God’s ways each day and appreciate the life given to them.
a heart of wisdom Wisdom starts with being properly oriented to God.
 Tozer, A. W., & Eggert, R. (2015). Tozer on the almighty god: a 365-day devotional. Chicago, IL: Moody Publishers.
 VanGemeren, W. A. (2008). Psalms. In T. Longman III & D. E. Garland (Eds.), The Expositor’s Bible Commentary: Psalms (Revised Edition) (Vol. 5, pp. 693–694). Grand Rapids, MI: Zondervan.
 MacDonald, W. (1995). Believer’s Bible Commentary: Old and New Testaments. (A. Farstad, Ed.) (pp. 688–689). Nashville: Thomas Nelson.
 MacArthur, J. F., Jr. (2006). The MacArthur study Bible: New American Standard Bible. (Ps 90:11–12). Nashville, TN: Thomas Nelson Publishers.
 Crossway Bibles. (2008). The ESV Study Bible (p. 1053). Wheaton, IL: Crossway Bibles.
 Barry, J. D., Mangum, D., Brown, D. R., Heiser, M. S., Custis, M., Ritzema, E., … Bomar, D. (2012, 2016). Faithlife Study Bible (Ps 90:11–12). Bellingham, WA: Lexham Press.