“For he knows our frame; He remembers that we are dust. As for man, his days are like grass; he flourishes like a flower of the field; for the wind passes over it, and it is gone, and its place knows it no more. But the steadfast love of the LORD is from everlasting to everlasting on those who fear Him, and His righteousness to children’s children, to those who keep His covenant and remember to do His commandments. The LORD has established His throne in the heavens, and His kingdom rules over all.” Psa 103:14-19
“For he knows how we are formed, he remembers that we are dust. David here annihilates all the worth which men would arrogate to themselves, and asserts that it is the consideration of our misery, and that alone, which moves God to exercise patience towards us. This again we ought carefully to mark, not only for the purpose of subduing the pride of our flesh, but also that a sense of our unworthiness may not prevent us from trusting in God. The more wretched and despicable our condition is, the more inclined is God to show mercy, for the remembrance that we are clay and dust is enough to incite him to do us good.
As for man, his days are like grass … the wind blows over it and it is gone, and its place remembers it no more. All the excellency of man withers away like a fading flower at the first blast of the wind. Although, as long as we live in this world, we are adorned with natural gifts, and “live, and move, and have our being in God” (Acts 17:28); yet as we have nothing except what is dependent on the will of another, and which may be taken from us every hour, our life is only a show or phantom that passes away. The subject here treated, is properly the brevity of life, to which God has a regard in so mercifully pardoning us, as it is said in another psalm—”He remembered that they were but flesh, a wind that passes away, and comes not again” (Ps. 78:39). If it is asked why David, making no mention of the soul, which yet is the principal part of man, declares us to be dust and clay, the answer is, that it is enough to induce God mercifully to sustain us, when he sees that nothing surpasses our life in frailty. And although the soul, after it has departed from the prison of the body, remains alive, yet its doing so does not arise from any inherent power of its own. Were God to withdraw his grace, the soul would be nothing more than a puff or blast, even as the body is dust; and thus there would doubtless be found in the whole man nothing but mere vanity.” _John Calvin