Niccolò Machiavelli
Discourses on the First Decade of Titus Livius (Chap. 2.26)
That Taunts and Abuse breed Hatred against him who uses them, without yielding him any Advantage.

To abstain from threats and injurious language, is, methinks, one of the wisest precautions a man can use. For abuse and menace take nothing from the strength of an adversary; the latter only making him more cautious, while the former inflames his hatred against you, and leads him to consider more diligently how he may cause you hurt.

This is seen from the example of the Veientines, of whom I spoke in the last Chapter, who, to the injury of war against the Romans, added those verbal injuries from which all prudent commanders should compel their soldiers to refrain. For these are injuries which stir and kindle your enemy to vengeance, and yet, as has been said, in no way disable him from doing you hurt; so that, in truth, they are weapons which wound those who use them. Of this we find a notable instance in Asia, in connection with the siege of Amida. For Gabade, the Persian general, after besieging this town for a great while, wearied out at last by its protracted defence, determined on withdrawing his army; and had actually begun to strike his camp, when the whole inhabitants of the place, elated by their success, came out upon the walls to taunt and upbraid their enemies with their cowardice and meanness of spirit, and to load them with every kind of abuse. Stung by these insults, Gabade, changing his resolution, renewed the siege with such fury that in a few days he stormed and sacked the town. And the very same thing befell the Veientines, who, not content, as we have seen, to make war on the Romans with arms, must needs assail them with foul reproaches, advancing to the palisade of their camp to revile them, and molesting them more with their tongues than with their swords, until the Roman soldiers, who at first were most unwilling to fight, forced the consuls to lead them to the attack. Whereupon, the Veientines, like those others of whom mention has just now been made, had to pay the penalty of their insolence.

Wise captains of armies, therefore, and prudent governors of cities, should take all fit precautions to prevent such insults and reproaches from being used by their soldiers and subjects, either amongst themselves or against an enemy. For when directed against an enemy they lead to the mischiefs above noticed, while still worse consequences may follow from our not preventing them among ourselves by such measures as sensible rulers have always taken for that purpose.

The legions who were left behind for the protection of Capua having, as shall in its place be told, conspired against the Capuans, their conspiracy led to a mutiny, which was presently suppressed by Valerius Corvinus; when, as one of the conditions on which the mutineers made their submission, it was declared that whosoever should thereafter upbraid any soldier of these legions with having taken part in this mutiny, should be visited with the severest punishment. So likewise, when Tiberius Gracchus was appointed, during the war with Hannibal, to command a body of slaves, whom the Romans in their straits for soldiers had furnished with arms, one of his first acts was to pass an order making it death for any to reproach his men with their servile origin. So mischievous a thing did the Romans esteem it to use insulting words to others, or to taunt them with their shame. Whether this be done in sport or earnest, nothing vexes men more, or rouses them to fiercer indignation; "for the biting jest which flavours too much of truth, leaves always behind it a rankling memory."[1]

[Footnote 1: Nam facetiæ asperæ, quando nimium ex vero traxere, acrem sui memoriam relinquunt. Tacit. An. xv. 68.]