Charles H. Spurgeon on Psalms 90:11

Who knoweth the power of thine anger? etc. The meaning is, What man doth truly know and acknowledge the power of thine anger, according to that measure of fear wherewith thou oughtest to be feared? Note hence, how Moses and the people of God, though they feared God, yet notwithstanding confess that they failed in respect of that measure of the feat of God which they ought to have had; for we must not think, but Moses and some of his people did truly fear God. But yet in regard of the power of God's anger, which was now very great and grievous, their fear of God was not answerable and proportionable; then it is apparent that Moses and his people failed in respect of the measure of the fear of God which they ought to have had, in regard of the greatness and grievousness of the judgments of God upon them. See, that the best of God's servants in this life fall short in their fear of God, and so in all graces of the Spirit; in that love of God, in faith in repentance, and in obedience, we come short all of us of that which the Lord requires at our hands. For though we do know God, and that he is a just God, and righteous, and cannot wink at sin; yet what man is there that so fears before him as he ought to be feared? what man so quakes at his anger as he should; and is so afraid of sin as he ought to be? We have no grace here in perfection, but the best faith is mixed with infidelity; our hope with fear; our joy with sorrow. It is well we can discern our wants and imperfections, and cry out with the man in the gospel, "I believe; Lord, help my unbelief!" —Samuel Smith.