Charles H. Spurgeon on Psalms 23:4

By the way, I note that David amidst his green pastures, where he wanted nothing, and in his greatest ease and highest excellency, recordeth the valley of misery and shade of death which might ensue, if God so would; and therewithal reckoneth of his safest harbour and firm repose, even in God alone. And this is true wisdom indeed, in fair weather to provide for a tempest; in health to think of sickness; in prosperity, peace, and quietness, to forecast the worst, and with the wise emmet, in summer to lay up for the winter following. The state of man is full of trouble, the condition of the godly man more. Sinners must be corrected, and sons chastised, there is no question. The ark was framed for the waters, the ship for the sea; and happy is the mariner that knoweth where to cast anchor; but, oh! blessed is the man that can take a right sanctuary, and knoweth whereupon to rely, and in whom to trust in the day of his need. "I will not fear, for thou art with me." In this Psalm, I take it, is rather vouched not what the prophet always performed, but what in duty must be performed, and what David's purpose was to endeavour unto for the time to come. For after so many pledges of God's infinite goodness, and by the guidance of his rod and stay of his sheep-hook, God willing, he would not fear, and this is the groundwork of his affiance. Peter in the gospel by our Saviour, in consideration of infirmity through fear denying his Master, is willed after his conversion by that favourable aspect of our Saviour, to confirm his brethren, and to train them in constancy; for verily God requireth settled minds, resolute men, and confirmed brethren. So upon occasions past, David found it true that he should not have been heretofore at any time, and therefore professeth, that for the time to come he would be no marigold-servant of the Lord, to open with the sun and shut with the dew —to serve him in calmer times only, and at a need, to shoot neck out of collar, fearfully and faithlessly to slip aside or shrink away. Good people, in all heartless imperfections, mark, I pray you, that they who fear every mist that ariseth, or cloud that appeareth —who are like the mulberry tree, that never shooteth forth or showeth itself till all hard weather be past —who, like standers-by and lookers on, neuters and internimists —who, like Metius Suffetius, dare not venture upon, nor enter into, nor endeavour any good action of greatest duty to God, prince, or country, till all be sure in one side —are utterly reproved by this ensample. John Prime, 1588.