7 Lastly, there follows the reason why I say this: “for You are my patience”. Now if He is patience rightly, He is that also which follows, “O Lord, my hope from my youth.” My patience, because my hope: or rather my hope, because my patience. “Tribulation,” says the Apostle, “works patience, patience probation, but probation hope, but hope confounds not.” With reason in You I have hoped, O Lord, I shall not be confounded for everlasting. “O Lord, my hope from my youth.”
From your youth is God your hope? Is He not also from your boyhood, and from your infancy? Certainly, says he. For see what follows, that you may not think that I have said this, “my hope from my youth,” as if God noways profited mine infancy or my boyhood; hear what follows: “In You I have been strengthened from the womb.” Hear yet: “From the belly of my mother You are my Protector”. Why then, “from my youth,” except it was the period from which I began to hope in You? For before in You I was not hoping, though You were my Protector, that led me safe unto the time, when I learned to hope in You.
But from my youth I began in You to hope, from the time when You armed me against the Devil, so that in the girding of Your host being armed with Your faith, love, hope, and the rest of Your gifts, I waged conflict against Your invisible enemies, and heard from the Apostle, “There is not for us a wrestling against flesh and blood, but against principalities, and powers,” etc. There a young man it is that does fight against these things: but though he be a young man, he falls, unless He be the hope of Him to whom he cries, “O Lord, my hope from my youth.”
“In You is my singing always.” Is it only from the time when I began to hope in You until now? Nay, but “alway.” What is, “alway”? Not only in the time of faith, but also in the time of sight. For now, “So long as we are in the body we are absent from the Lord: for by faith we walk, not by sight:” there will be a time when we shall see that which being not seen we believe: but when that has been seen which we believe, we shall rejoice: but when that has been seen which they believed not, ungodly men shall be confounded.
Then will come the substance whereof there is now the hope. But, “Hope which is seen is not hope. But if that which we see not we hope for, through patience we wait for it.” Now then you groan, now unto a place of refuge you run, in order that you may be saved; now being in infirmity you entreat the Physician: what, when you shall have received perfect soundness also, what when you shall have been made “equal to the Angels of God,” will you then perchance forget that grace, whereby you have been delivered? Far be it.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)