Verse 21. - For our heart shall rejoice in him, because we have trusted in his holy Name (comp. Psalm 13:5, where the sentiment is the same). Trust in God secures his help, and this brings the deliverance at which the heart rejoices.

33:12-22 All the motions and operations of the souls of men, which no mortals know but themselves, God knows better than they do. Their hearts, as well as their times, are all in his hand; he formed the spirit of each man within him. All the powers of the creature depend upon him, and are of no account, of no avail at all, without him. If we make God's favour sure towards us, then we need not fear whatever is against us. We are to give to him the glory of his special grace. All human devices for the salvation of our souls are vain; but the Lord's watchful eye is over those whose conscientious fear of his name proceeds from a believing hope in his mercy. In difficulties they shall be helped; in dangers they shall not receive any real damage. Those that fear God and his wrath, must hope in God and his mercy; for there is no flying from him, but by flying to him. Let thy mercy, O Lord, be upon us; let us always have the comfort and benefit, not according to our merits, but according to the promise which thou hast in thy word given to us, and according to the faith thou hast by thy Spirit and grace wrought in us.For our heart shall rejoice in him,.... Not in sin, nor in themselves and in their boastings, all such rejoicing is evil; but in the Lord, "in his Word"; as the Targum is, in the essential Word of God, Christ Jesus; in his person, righteousness, and salvation; and this joy is heart joy, inward joy, real joy, joy in the Holy Ghost; and is unspeakable and full of glory. This is what the psalmist calls upon the saints to do, in the beginning of the psalm; and so his end in composing it is answered;

because we have trusted in his holy name; that is, in himself, who is holy, just, and good; and so faithful to every word of promise, to every engagement of his, and therefore to be trusted in: and hence it appears that the joy before spoken of is the joy of faith.