John Calvin Commentary Psalms 40:16

"Let all those that seek thee rejoice and be glad in thee: Let such as love thy salvation say continually, Jehovah be magnified." — Psalms 40:16 (ASV)

Let all those that seek you be glad and rejoice in you. David here uses another argument—one which he often brings forward elsewhere—in order to obtain deliverance; not that it is necessary to present reasons to persuade God, but because it is beneficial to confirm our faith with such supports.

So, since it is God's will to be known in His gracious character by the generality of all people, not just one or two, whenever He grants deliverance to any of His children, it is a common benefit. All the faithful should apply this to themselves when they see in one person how God, who is never inconsistent with Himself, will act towards all His people.

David, therefore, shows that he asks nothing for himself individually but what pertains to the whole Church. He prays that God would gladden the hearts of all the saints, or give them all common cause for rejoicing, so that, assured of His readiness to help them, they may turn to Him with greater eagerness.

Therefore, we conclude that, for each individual, God gives a proof of His goodness towards us. What is added, those that love your salvation, also deserves our attention. From this, we may infer that our faith is proven genuine only when we neither expect nor desire preservation except from God alone.

Those who devise various methods of self-preservation in this world despise and reject the salvation which God has taught us to expect from Him alone. What had been said before, those who seek you, serves the same purpose. If an individual wishes to depend wholly upon God and desire to be saved by His grace, he must renounce every vain hope and direct all his thoughts toward receiving His strength.

Here, again, we must observe that two things are contrasted with each other. Formerly David had said that the wicked sought his life; now he attributes to the faithful a very different feeling, namely, that they seek God. Likewise, he had described the reproaches and derision of the ungodly, while they said, Aha, aha! and now he introduces the godly speaking very differently, saying, The Lord be magnified!