John Trapp on Proverbs 26:3

Verſ. 3. A whip for the horſe] Viz. To quicken his ſlow pace. A bridle for the aſſe, wherewith to lead him in the right way: for he goes willingly but a foot-pace, and would be oft out, but for the bit, and beſides, he is very refractory, and muſt be held in with bit and bridle, Pſal. 32.9.

And a rod for the back of fools] [non-Latin text not transcribed]. A fool will be the better for beating. Vexatio dat intellectum. Due puniſhment may well be to theſe horſes and aſſes (ſo the Scripture terms unreaſonable and wicked men) both for a whip to incite them to good, and for a bridle to reign them in from evil. God hath rods ſticking in every corner of his houſe for theſe froward fools, and if a rod ſerve not turn, he hath a terrible ſword, Eſay 27.1. So muſt Magiſtrates. Cuncta prius tentanda. If a rod will do, they need not brandiſh the ſword of Juſtice; nor do as Draco did, who puniſhed with death every light offence. This was to kill a fly upon a mans forehead with a beetle, to the knocking out of his brains.