Solomon
Proverbs 15:13ESV·traditional attribution

A glad heart makes a cheerful face, but by sorrow of heart the spirit is crushed.

Matthew Henry Presbyterian @wholebiblehenry

Here, 1. Harmless mirth is recommended to us, as that which contributes to the health of the body, making men lively and fit for business, and to the acceptableness of the conversation, making the face to shine and rendering us pleasant one to another.

John Gill Reformed Baptist @doctorgill

A merry heart maketh a cheerful countenance,.... Or, a "joyful heart" (c); that is joyful in the God of its salvation; that rejoices in Christ Jesus; is filled with joy and peace through believing in him, in his person, blood, righteousness, and sacrifice; that has a comfortable view of his justification by his righteousness, of peace and pardon by his blood, of the atonement of...

Jamieson-Fausset-Brown Reformed @jfbcommentary

maketh . . . countenance--or, "benefits the countenance." spirit is broken--and so the countenance is sad.