Charles H. Spurgeon on Psalms 9:6

Here the Psalmist exults over the fallen foe. He bends as it were, over his prostrate form, and insults his once vaunted strength. He plucks the boaster's song out of his mouth, and sings it for him in derision. After this fashion doth our Glorious Redeemer ask of death, "Where is thy sting?" and of the grave, "Where is thy victory?" The spoiler is spoiled, and he who made captive is led into captivity himself. Let the daughters of Jerusalem go forth to meet their King, and praise him with timbrel and harp.

In the light of the past the future is not doubtful. Since the same Almighty God fills the throne of power, we can with unhesitating confidence, exult in our security for all time to come.