John Calvin Commentary Psalms 86:5

"For thou, Lord, art good, and ready to forgive, And abundant in lovingkindness unto all them that call upon thee." — Psalms 86:5 (ASV)

For you, O Lord, are good and propitious. We have here a confirmation of the whole preceding doctrine, derived from the nature of God. It would be of no use to the afflicted to turn to him, and to lift up their desires and prayers to heaven, if they were not persuaded that he is a faithful rewarder of all who call upon him.

The point David now emphasizes is that God is generous and compassionate, and that his mercy is so great that it is impossible for him to reject any who plead for his help. He calls God propitious, or ascribes to him the attribute of pardoning sin, which is a modification of his goodness. It would not be enough for God to be good in general if he did not also extend to sinners his forgiving mercy, which is the meaning of the word סלה, salach.

Furthermore, although David emphasizes the abundance of God’s mercy, he immediately afterward represents this abundance as restricted to the faithful who call upon him. This teaches us that those who, disregarding God, stubbornly resist, deservedly perish in their calamities. At the same time, he uses the term all, so that everyone, without exception, from the greatest to the least, may be encouraged to confidently turn to the goodness and mercy of God.