David
Psalm 103:15ESV·traditional attribution

As for man, his days are like grass; he flourishes like a flower of the field;

John Calvin Reformed @genevareformer

PSALM 103 By this psalm every godly man is taught to give thanks to God for the mercies bestowed upon himself in particular, and then for the grace which God has vouchsafed to all his chosen ones in common, by making a covenant of salvation with them in his law, that he might make them partakers of his adoption.

Commenting on Psalm 103:1-22

C.H. Spurgeon Reformed Baptist @princeofpreachers

As for man, his days are as grass. He lives on the grass, and lives like the grass. Corn is but educated grass, and man, who feeds on it, partakes of its nature. The grass lives, grows, flowers, falls beneath the scythe, dries up, and is removed from the field: read this sentence over again, and you will find it the history of man.

Matthew Henry Presbyterian @wholebiblehenry

Hitherto the psalmist had only looked back upon his own experiences and thence fetched matter for praise; here he looks abroad and takes notice of his favour to others also; for in them we should rejoice and give thanks for them, all the saints being fed at a common table and sharing in the same blessings. I.

Commenting on Psalm 103:6-18