"Trust in the LORD, and do good; so shalt thou dwell in the land, and verily thou shalt be fed." (Psalm 37:3)
Although there are many promises in Scripture to the effect that the Lord will provide material sustenance to those who are faithful to Him (Matthew 6:33), this particular verse evidently refers to an even more blessed promise. The word translated "verily" is better rendered by "truth," so the latter part of the verse could best be given as: "thou shalt be fed on the truth." That is, the spiritual life of the one who trusts in Christ will be fed and sustained by truth.
In contrast, the unbeliever feeds on that which is not true. The one "who hath formed a god" (Isaiah 44:10) for himself will soon taste bitterness on his tongue. "He feedeth on ashes: a deceived heart hath turned him aside, that he cannot deliver his soul, nor say, Is there not a lie in my right hand?" (Isaiah 44:20). Those who trust in human deliverance will be like Israel depending on Egypt and Assyria. "Ephraim feedeth on wind, and followeth after the east wind: he daily increaseth lies and desolation" (Hosea 12:1). The diet of false prophets is more bitter still. "Therefore thus saith the LORD of hosts concerning the prophets; Behold, I will feed them with wormwood, and make them drink the water of gall" (Jeremiah 23:15).
Wind and ashes, wormwood and gall; such is the spiritual food of those who reject the truth of the Word of God.
To the believer, however, the Scriptures are as much a daily need for the soul as bread for the body. As Job said long ago: "I have esteemed the words of his mouth more than my necessary food" (Job 23:12). Moses testified as follows: "And he humbled thee, and suffered thee to hunger, and fed thee with manna, which thou knewest not, neither did thy fathers know; that he might make thee know that man doth not live by bread only, but by every word that proceedeth out of the mouth of the LORD" (Deuteronomy 8:3). HMM