What proof is there in my blood - That is, What profit or advantage would there be to thee if I should die? What would be “gained” by it? The argument which the psalmist urges is that he could better serve God by his life than by his death; that his death, by removing him from the earth, would prevent his rendering the service which he might by his life. The same argument is presented also in Psalms 6:5 (see the notes at that verse), and is found again in Psalms 88:10-12, and in the hymn of Hezekiah, Isaiah 38:18-19. See the notes at that passage. The prayer used here is to be understood, not as a prayer at the time of the composition of the psalm, but as that which the psalmist employed at the time when he thought his mountain stood strong, and when God saw suitable to humble him by some calamity - perhaps by a dangerous illness, Psalms 30:6-7.
When I go down to the pit? - To the grave; or, If I should go down to the grave. See the notes at Psalms 30:3.
Shall the dust praise thee? - That which turns to dust; the lifeless remains. See the notes at Psalms 6:5.
Shall it declare thy truth? - Can a lifeless body stand up in defense of the truth, or make that truth known to the living? This shows on what his heart was really set, or what was the prevailing desire of his soul. It was to make known the truth of God; to celebrate his praise; to bring others to an acquaintance with him. It cannot be denied that the statement here made is founded on obscure views, or on a misconception of the condition of the soul after death - a misconception which we are enabled to correct by the clearer light of the Christian religion; but still there is a truth here of great importance. It is, that whatever we are to do for making known the character and perfections of God on earth - for bringing others to the knowledge of the truth, and saving their souls - is to be done before we go down to the grave. whatever we may do to honor God in the future world - in the vast eternity on which we enter at death - yet all that we are to do in this respect on earth is to be accomplished before the eyes are closed, and the lips are made mute in death. We shall not return to do what we have omitted to do on earth; we shall not come back to repair the evils of an inconsistent life; we shall not revisit the world to check the progress of error that we may have maintained; we shall not return to warn the sinners whom we neglected to warn. Our work on earth will be soon done - and done finally and forever. If we are to offer prayer for the salvation of our children, neighbors, or friends, it is to be done in this world; if we are to admonish and warn the wicked, it is to be done here; if we are to do anything by personal effort for the spread of the Gospel, it is to be done before we die. Whatever we may do in heaven, these things are not to be done there, for when we close our eyes in death, our personal efforts for the salvation of men will cease for ever.