Solomon
Ecclesiastes 10:20ESV·traditional attribution

Even in your thoughts, do not curse the king, nor in your bedroom curse the rich, for a bird of the air will carry your voice, or some winged creature tell the matter.

Matthew Henry Presbyterian @wholebiblehenry

Solomon here observes, I. How much the happiness of a land depends upon the character of its rulers; it is well or ill with the people according as the princes are good or bad. 1. The people cannot be happy when their princes are childish and voluptuous (Ecc 10:16): Woe unto thee, O land!

Commenting on Ecclesiastes 10:16-20

John Gill Reformed Baptist @doctorgill

Curse not the king; no, not in thy thought,.... Though he is a child, and unskilful in government, gives himself to his passions and pleasures, and neglects the affairs of the kingdom; yet be so far from rebelling against him, and doing him any injury, or speaking ill of him, as not even to wish him any ill; or, within thine own breast, imprecate any...

Jamieson-Fausset-Brown Reformed @jfbcommentary

thought--literally, "consciousness." rich--the great. The language, as applied to earthly princes knowing the "thought," is figurative. But it literally holds good of the King of kings (Psa. 139:1-24), whose consciousness of every evil thought we should ever realize. bed-chamber--the most secret place (Kg2 6:12).