John Trapp Complete Commentary
Proverbs 14:5
A faithful witness will not lie: but a false witness will utter lies.
Ver. 5. A faithful witness will not lie.] Nec prece nec precio, he cannot lend an oath for a need before a magistrate. Nay, he will not lie upon any condition. See Trapp on " Pro 13:5 "
But a false witness will utter lies.] Or, He that telleth lies will be a false witness - he that makes light of a lie will not stick at perjury. That was a foul blur to the Romans of old, if true, that Mirrhanes the Persian general chargeth upon them, Romanis promittere promptum est, promissis autem quanqum iuramento firmatis minime stare; a the Romans will presently promise anything, but perform no promise though confirmed with an oath. Of the Romists at this day it is written by an Italian, no stranger to the court of Rome, that their proverb is, Mercatorum est, non regum, stare iuramentis; It is for merchants, not for princes, to stand to what they have sworn. Fides cum hereticis non est servanda is their position, and their practice is accordingly. They play with oaths as the monkey doth with his collar, which he doth slip on for his master's pleasure, and slip off again for his own. Pascenius scoffs King James for the invention of the oath of allegiance.
a Procop., lib. i. de bello Persico.