Albert Barnes Commentary Psalms 141:7

"As when one ploweth and cleaveth the earth, Our bones are scattered at the mouth of Sheol." — Psalms 141:7 (ASV)

Our bones are scattered at the grave’s mouth—We are, indeed, now like bones scattered in the places of graves; we seem to be weak, feeble, and disorganized. We are in a condition that in itself seems to be hopeless, as hopeless as it would be for dry bones, scattered when they were buried, to rise up and attack an enemy.

The reference is to the condition of David and his followers as they were pursued by a mighty foe. His hope was not in his own forces, but in the power and interposition of God (Psalms 141:8).

As when one cutteth and cleaveth wood upon the earth—Like chips, blocks, and splinters that have no strength; as when these lie scattered around—a fitting emblem of our feeble and scattered forces.