To you. O LORD, I lift up my soul. The Psalmist declares at the very outset, that he is not driven here and there, after the manner of the ungodly, but that he directs all his desires and prayers to God alone. Nothing is more inconsistent with true and sincere prayer to God, than to waver and gaze about as the heathen do, fro some help from the world; and at the same time to forsake God, or not to betake ourselves directly to his guardianship and protection. In order to strengthen the hope of obtaining his request, he declares, what is of the greatest importance in prayer, that he had his hope fixed in God, and that he was not ensnared by the allurements of the world, or prevented from lifting up his soul fully and unfeignedly to God. In order, therefore, that we may pray aright to God, let us be directed by this rule: not to distract our minds by various and uncertain hopes, nor to depend on worldly aid, but to yield to God the honor of lifting up our hearts to him in sincere and earnest prayer.
In you I trust, O my God. Do not let me be put to shame, nor let my enemies triumph over me. By the word trust David confirms that faith and hope are added as the cause of such an effect, namely, the lifting up of the soul. And, indeed, these are the wings by which our souls, rising above this world, are lifted up to God. David, then, was carried upwards to God with the whole desire of his heart, because, trusting to his promises, he thereby hoped for sure salvation. When he asks that God would not let him be put to shame, he offers up a prayer, which is taken from the ordinary doctrine of Scripture, namely, that they who trust in God shall never be ashamed. The reason which is added, is that he might not be exposed to the derision of his enemies, whose pride is no less hurtful to the feelings of the godly than it is displeasing to God.
No one whose hope is in you will ever be put to shame, but they will be put to shame who are treacherous without excuse. David declares that when he is delivered he will not enjoy exclusively the benefit of it; but that its fruit shall extend to all true believers; just as on the other hand, the faith of many would be shaken if he had been forsaken by God.
-Heart Aflame: Daily Readings From Calvin on the Psalms, by John Calvin