But you, O Lord, are a God merciful and gracious, slow to anger and abounding in steadfast love and faithfulness.
Proud and violent men are closing in on David, and they have no regard for God (v. 14). At that exact point he turns from what his enemies are to what God is. Verse 15 is not new language. It repeats the description of Himself that God once gave to Moses, now pressed into a prayer.
The contrast that changes everything
The "But" at the start of the verse sets God's character against the men who are hunting the psalmist. One commentator reads the whole movement of these closing verses that way:
Hamilton SmithStill, if the wicked are against the psalmist, God is for him. And the God who is for him is full of compassion, gracious, long-suffering, and plentiful in mercy and truth. So he pleads with God. Though men turn against him, may God turn towards him, strengthen him, and save him from his enemies.
Quoting the name God gave to Moses
God announced His own name in these words to Moses (Exodus 34:6-7). The psalmist remembers that name and prays it back to God.
C E StuartThe suffering saint has already known mercy, for God kept him from death (13). He still looks for mercy, remembering the revelation of the Divine name to Moses (15, 16). What a support that revelation of God (Ex. 34:6-7) has been to believers age after age, as the Old Testament shows!
Mercy for all who call
The same writer notes the ground the prayer started on:
C E StuartA prayer of David (86), the words of an individual believer, addressing God in the consciousness of what God is, and can be, in grace — good, and ready to forgive, and plentiful in mercy to all who call on Him (5).
"Slow to anger" — patience aimed at people
The phrase describes restraint that is personal. It is God holding back from those who give Him every reason not to.
J. A. TrenchExpressing then "a long holding out of the mind before it gives room to action or passion," it is applied to God, in His forbearance towards those who provoke Him.
In trial, this patience can be hard to bear:
J. N. DarbyHe is slow to anger — perhaps the heart has complained of that sometimes in trial, yet we need it — and of great mercy. Yes, we are often Jonahs, though we need or have needed as much mercy as Nineveh.
Mercy and truth in one sentence
The verse ends by pairing two things that can look like rivals. Older translations say "full of compassion" and "mercy and truth" where the ESV says "merciful" and "steadfast love and faithfulness." Holding the two together raises a real question:
F. B. HoleHere we have features of God's character brought together. We now know them quite well, but to Moses they might have seemed in many ways to clash with each other. He might have wanted to ask: if He is abundant in truth as well as goodness, how can He be gracious to a people such as we have proved ourselves to be?… But even so, there was no full display of "grace and truth" until they "came by Jesus Christ" (John 1:17). His death and resurrection brought them together in harmony.
Compassion that reaches the undeserving
This character is not reserved for the deserving. It shows itself in ordinary kindness to people who never thank Him for it:
William KellyThe Lord is a God full of compassion and gracious, slow to anger and plentiful in mercy, even when man is under law… How kind to the unthankful and the indifferent, the infatuated and evil! For what purpose, except that such may gain wisdom? Seeing he is without sense draws out His pity.
Compassion known in trouble
Verse 15 is a discovery made in prayer, not a doctrine recited at a distance. What follows it in verse 16 is a fresh request, because knowing God's character makes asking natural:
L M GrantIn the very presence of God the psalmist finds Him to be "a God full of compassion and gracious, long-suffering and abundant in mercy and truth" (v. 15). Wonderful resting place for faith! To be in the shelter of God's presence is far more blessed than any other place one could desire.
The same pattern repeats in the New Testament, where trouble becomes the very place God's comfort is felt:
Hamilton SmithThese trials came from inside and outside the Christian circle. Yet they became the occasion of experiencing the "compassions" and "comforts" of God. David went through similar experiences in his own day. When the proud rose up against him, and violent men sought his life, he could say: "But you, O Lord, are a God full of compassion," and "you, LORD, have helped me and comforted me" (Ps. 86:14-17).
Summary
- Source — The words come from God's own announcement of His name to Moses in Exodus 34:6-7. That description has steadied believers "age after age."
- Contrast — "But" turns the prayer. Enemies press in, and the psalmist answers by naming what God is.
- Patience — "Slow to anger" means God holds back from the very people who provoke Him. We are often Jonahs, needing as much mercy as Nineveh.
- Reach — That kindness reaches the unthankful and the indifferent, so that they may gain wisdom.
- Result — Mercy and truth stand side by side in this verse. Commentators say their full display came in Jesus Christ, and His comfort is met in the middle of trouble.