Who knoweth the power of thine anger? even according to thy fear, so is thy wrath.
-The Second part, First division. The mysterious relation of death to sin, as its wages, is little, if at all, known by man; therefore the Psalmist prays, God so teach us it as to lead us to wisdom of the heart.
Verse 11. Who knoweth the power of thine anger? - Who knows aright thy powerful anger, as manifested in the brevity of our existence, and the power that death is permitted to have over us? In this sad lament over man's insensibility, in not perceiving in this his short-lived and miserable state the expression of God's just wrath against man's sin, there is involved the desire that God would take away man's insensibility; the corresponding prayer follows in Psalms 90:12.
Even according to thy fear, (so is) thy wrath - according to thy dreadfulness, so is thy wrath against sin. Rather omit so is (not in the Hebrew), and translate, 'Who knoweth ... thine, anger, and thy wrath in proportion to thy fear? - i:e., in proportion to what reverential fear of thee requires. So "thy fear" is used (Psalms 5:7).
Verse 12. So teach us to number our days. The same Hebrew is used for "teach" here as is used for "knoweth," Psalms 90:11. Translate, 'How to number our days, so make us to know.' The "so" х keen (H3651)] marks the infinite importance of this knowledge, which is to be learnt only from God, not by natural ability. The object for which he wishes God to 'make us men know how to number our days' is in order that we may 'know the power of God's anger,' as caused by our sin, and manifested in our short-lived and miserable existence (Psalms 90:11), and so - "that we may apply our hearts unto wisdom"
That we may apply our hearts unto wisdom - literally, 'that we may make to come to us a wise heart,' or 'that we may make wisdom to come (into) our heart.' The "wisdom" meant is that which flows from a right consideration of the brevity of life, and our guiltiness as the cause of God's, anger against us; and consists in "fearing God" and "departing from evil" (Job 28:28). The sentiment in this psalm of Moses is in beautiful and undesigned coincidence with Moses' historical book (Deuteronomy 32:19), Compare also Deuteronomy 4:6. By such "wisdom" the way is prepared for God to grant the following prayer, that He would return and gladden us with His mercy.