Complete Commentary on the Whole Bible, by Matthew Henry, at sacred-texts.com
(Psa 9:1-10) David praises God for protecting his people.
(Psa 9:11-20) And for cause to praise him.
If we would praise God acceptably, we must praise him in sincerity, with our whole heart. When we give thanks for some one particular mercy, we should remember former mercies. Our joy must not be in the gift, so much as in the Giver. The triumphs of the Redeemer ought to be the triumphs of the redeemed. The almighty power of God is that which the strongest and stoutest of his enemies are no way able to stand before. We are sure that the judgment of God is according to truth, and that with him there is no unrighteousness. His people may, by faith, flee to him as their Refuge, and may depend on his power and promise for their safety, so that no real hurt shall be done to them. Those who know him to be a God of truth and faithfulness, will rejoice in his word of promise, and rest upon that. Those who know him to be an everlasting Father, will trust him with their souls as their main care, and trust in him at all times, even to the end; and by constant care seek to approve themselves to him in the whole course of their lives. Who is there that would not seek him, who never hath forsaken those that seek Him?
Those who believe that God is greatly to be praised, not only desire to praise him better themselves, but desire that others may join with them. There is a day coming, when it will appear that he has not forgotten the cry of the humble; neither the cry of their blood, or the cry of their prayers. We are never brought so low, so near to death, but God can raise us up. If he has saved us from spiritual and eternal death, we may thence hope, that in all our distresses he will be a very present help to us. The overruling providence of God frequently so orders it, that persecutors and oppressors are brought to ruin by the projects they formed to destroy the people of God. Drunkards kill themselves; prodigals beggar themselves; the contentious bring mischief upon themselves: thus men's sins may be read in their punishment, and it becomes plain to all, that the destruction of sinners is of themselves. All wickedness came originally with the wicked one from hell; and those who continue in sin, must go to that place of torment. The true state, both of nations and of individuals, may be correctly estimated by this one rule, whether in their doings they remember or forget God. David encourages the people of God to wait for his salvation, though it should be long deferred. God will make it appear that he never did forget them: it is not possible he should. Strange that man, dust in his and about him, should yet need some sharp affliction, some severe visitation from God, to bring him to the knowledge of himself, and make him feel who and what he is.