Shall thy loving-kindness be declared in the grave? - Thy goodness; thy mercy. Shall anyone make it known there? shall it there be celebrated?
Or thy faithfulness in destruction? - In the place where destruction seems to reign; where human hopes perish; where the body moulders back to dust. Shall anyone there dwell on the fidelity - the truthfulness - of God, in such a way as to honor him? It is implied here that, according to the views then entertained of the state of the dead, those things would not occur. According to what is now made known to us of the unseen world it is true that the mercy of God will not be made known to the dead; that the Gospel will not be preached to them; that no messenger from God will convey to them the offers of salvation. Compare Luke 16:28-31.

Or thy faithfulness in destruction? - Faithfulness in God refers as well to his fulfilling his threatenings as to his keeping his promises. The wicked are threatened with such punishments as their crimes have deserved; but annihilation is no punishment. God therefore does not intend to annihilate the wicked; their destruction cannot declare the faithfulness of God.

Shall thy lovingkindness be declared in the grave?.... Where he saw himself now going, and where should he be detained, and not raised out of it, the lovingkindness of God to him, as his Son, and as man and Mediator, and to his people in the gift and mission of him to be their Saviour and Redeemer, how would that be declared and made known? now it is, Christ being raised, and his ministers having a commission from him to preach the Gospel, in which the lovingkindness of God is abundantly manifested:
or thy faithfulness in destruction? the grave, so called from dead bodies being cast into it, and wasted, consumed, and destroyed in it: the meaning may be, that should he be laid in the grave, and there putrefy and rot, and not be raised again, where would be the faithfulness of God to his purposes, to his covenant and promises, to him his Son, and to his people?

amplify the foregoing, the whole purport (as Psalm 6:5) being to contrast death and life as seasons for praising God.