Solomon
Ecclesiastes 3:18ESV·traditional attribution

I said in my heart with regard to the children of man that God is testing them that they may see that they themselves are but beasts.

Matthew Henry Presbyterian @wholebiblehenry

Solomon is still showing that every thing in this world, without piety and the fear of God, is vanity. Take away religion, and there is nothing valuable among men, nothing for the sake of which a wise man would think it worth while to live in this world.

Commenting on Ecclesiastes 3:16-22

John Gill Reformed Baptist @doctorgill

I said in mine heart concerning the estate of the sons of men,.... He thought of the condition of the children of men, their sinful and polluted state; he weighed and considered in his mind their actions, conversation, and course of life; and was concerned how it would go with them at the day of judgment on account of the same.

Jamieson-Fausset-Brown Reformed @jfbcommentary

estate--The estate of fallen man is so ordered (these wrongs are permitted), that God might "manifest," that is, thereby prove them, and that they might themselves see their mortal frailty, like that of the beasts. sons of men--rather, "sons of Adam," a phrase used for "fallen men." The toleration of injustice until the judgment is designed to "manifest" men's characters in their fallen state, to...