John Calvin Commentary Psalms 63:5

"My soul shall be satisfied as with marrow and fatness; And my mouth shall praise thee with joyful lips;" — Psalms 63:5 (ASV)

My soul shall be satisfied as with marrow, etc. In accordance with what was said in the previous verse, David expresses his assured conviction of obtaining a rich and abundant measure of every blessing that could call for thanksgiving and praise. At the time of composing this psalm, he may have already been enjoying ease and plenty; but there is reason to believe that he cherished this conviction, even when wandering in the wilderness in a state of poverty and destitution.

If we are to show strong faith, we must anticipate God's favor before it has actually been manifested, and when there is no current sign of its coming. From the example set before us here, we must learn to guard against despondency, in circumstances when we may see the wicked wallowing and rioting in the abundance of the things of this world, while we ourselves are left to pine from lacking them.

David, in the current pressure he faced, might have given way to despair, but he knew that God was able to fill the hungry soul, and that he would lack nothing as long as he possessed God's favor. It is God’s will to test our patience in this life with various kinds of afflictions. Let us bear the wrongs that may be done to us with meekness, until the time comes when all our desires will be abundantly satisfied.

It should be noted that David, when he speaks in figurative language of being filled with marrow and fatness, does not mean that intemperate and excessive indulgence to which ungodly people surrender themselves, and by which they brutify their minds. He looks forward to that moderate measure of enjoyment which would only spur him to greater alacrity in praising God.