Solomon
Proverbs 20:28ESV·traditional attribution

Steadfast love and faithfulness preserve the king, and by steadfast love his throne is upheld.

Matthew Henry Presbyterian @wholebiblehenry

Here we have, 1. The virtues of a good king. Those are mercy and truth, especially mercy, for that is mentioned twice here. He must be strictly faithful to his word, must be sincere, and abhor all dissimulation, must religiously discharge all the trusts reposed in him, must support and countenance truth. He must likewise rule with clemency, and by all acts of compassion gain the affections of his people.

John Gill Reformed Baptist @doctorgill

Mercy and truth preserve the king,.... Which are two good qualifications in a prince; not ruling his subjects with rigour and cruelty, but with tenderness and clemency; easing them as much as he can of burdens and pressures; showing compassion to the distressed, and pardoning delinquents when the case will admit of it; as also being faithful to his word, promises, and engagements; inviolably adhering...

Keil & Delitzsch Lutheran @keilanddelitzsch

Pro 20:28 28 Love and truth guard the king; And he supports his throne by love. We have not in the German [nor in the Eng.] language a couple of words that completely cover חסד ואמת; when they are used of God, we translate them by grace and truth [Gnade u. Wahrheit], Psa 40:12 (יצּרוּני); when of men, by love and truth [Liebe u.