John Calvin Commentary Psalms 37:39

"But the salvation of the righteous is of Jehovah; He is their stronghold in the time of trouble." — Psalms 37:39 (ASV)

The salvation of the righteous is from Jehovah. The essence of it all is that whatever may happen, the righteous will be saved, because they are in the hand of God and can never be forgotten by him.

This should be particularly noted, so that those who are greatly afflicted may be sustained by the assurance that the salvation they expect from God is infallibly certain. This certainty arises because God is eternal and governs the world by his power, as Christ said, My Father, who gave them me, is greater than all (John 10:29).

David further emphasizes this principle: since righteousness is approved by God, he will never forsake his faithful servants or deprive them of his help.

Therefore, he urges true believers to depend on God, not only when things prosper according to their desires, but even when they are severely afflicted.

By these words, he teaches that it is enough if God only gives strength to his servants, so that when severely afflicted and oppressed with anguish, they do not faint under it, or, when groaning under the weight of severe afflictions, they do not sink under the burden.

The expression David uses twice in the last verse, that God will deliver, also serves this same purpose.

By this, he urges the children of God to learn to patiently endure afflictions. If God should prolong them, they should often recall that after he has tested their patience, he will in the end deliver them.